* Adding unit tests for magic (streamlit#13)

* Adding unit tests for magic

* Standardize cypress viewport across all tests and fixes (streamlit#11)

- standardize cypress viewport across all tests
- remove snapshot corresponding to missing `mplotlib` test
- fixed issue with snapshots being cutoff or wrong element being captured sporadically
- increased snapshot diff threshold by .5%
- increase snapshot bounding box for `disconnect.py` and `empty_dataframes.py`
- allow multiple valid width values for `vega_lite_chart.py`
- set `devicePixelRatio` to 1 when running `cypress open'
- remove spinner e2e test and core example
- fix various cypress tests
- preload `viz.js` when running `yarn start`

* Deprecating data parameter from st.deck_gl_chart() (streamlit#22)

* Deprecating data parameter for st.deck_gl_chart()

* Basic deck_gl example setting viewport

* DOCSTRING

* LINT

* Moving deck_gl_chart test from streamlit_test to deck_gl_test

* Checking kwargs instead of a data parameter

* Fixing comments from thiago

* st.image() resizing images when are bigger than the maximum (streamlit#30)

* Resizing image when its bigger than the maximum width

* Resizing image when its bigger than the maximum width

* MAXIMUM_CONTENT_WIDTH documentation

* MAXIMUM_CONTENT_WIDTH documentation

* Hash numpy arrays. Use fixed size sample. (streamlit#16)

* Merge version 0.45.0 (streamlit#34)

* Restore correct vertical spacing for report elements.

* Break Block.tsx into more functions.

* Tiny refactors in Block.tsx

* Add "key" property to element in DocString, to avoid warnings.

* Fix streamlit#1230: OSError not caught when writing cache to disk

* Don't show hashing warning when user imports a module inside a cached function.

* Fix streamlit#6: report should loads element by element (was broken since Sidebar PR)

* Try to fix CircleCI issue: Method 'renderElementWithErrorBoundary' expected no return value

* Add typing to function.

* Remove unecessary dockerfiles

* Fix a bunch of examples

* Fix color of syntax error code in modal dialog.

* Remove old style copyright from conftest.py

* Remove st.warning when hashing a class.

* Add astor to Python requirements

* Update widget API in some e2e tests

* Clean up st.foo_widget() signatures in st.help()

* Lint docs/getting_started.md

* Clean up widget examples in docstrings.

* Add comment to slider examples in docs.

* Tweak Streamlit's description in setup.py

* Sort pipfile modules

* Re-add scripts and Makefile rules to publish packages to conda.

* Fix update_version.py to support new conda location and remove old docker folder.

* Make `streamlit config show` pipeable to a file.

* Update docs/ site

* Remove /docs/api invalidation from Makefile

* Improve docstring for st.slider

* Remove st.Cache (capital C) from __init__ while we figure out what to call it.

* Up version to 0.45.0

* Turn off tests for st.Cache (capital C)

* Try turning off tests again

* Test frontend in CircleCI (streamlit#35)

* CircleCI: run frontend tests after python tests

* `make jstest`: don't run non-existent 'coverage' script

* Add `make jscoverage` in case we want to use it

* Make sure we generate scssvars

* Conditionally run our frontend tests

* 403 Error message (streamlit#37)

* 403 Error message

* ESLint

* Adding width and height parameter to st.dataframe (streamlit#33)

This PR proposes to add a width and height parameter to st.dataframe. Protobuf is changed to include an ElementDimensionSpec field to carry this information. This is included as part of the forward message metadata. The message is parsed and height/width information is extracted and passed down to the Dataframe React component in Block.tsx. Width is set in Block.tsx since existing logic applies to a generic element, while height is set in the Dataframe element in some ad hoc logic.

* Fix WebsocketConnection totalTries count (streamlit#38)

* Fixing overlap between onload and onreadystatechange

* Removing unused events

This implements `ForwardMsgCache` expiration on both the client and the server.

- The `global.maxCachedMessageAge` config value specifies the maximum age of a message in the cache. The age of a message is defined by the number of times a referencing report has finished running since the message was accessed by that report. So when a report finishes running for the first time, the age of all its cached messages is 1.
- Our default maxCachedMessageAge is 2, which means that messages will remain cached even after not having been referenced for a report run.
- To determine the age of messages in its cache, the server tracks a `report_run_count` alongside each `ReportSession` in its websocket->reportsession dictionary. The server increments this value each time it processes a `report_finished` ForwardMsg message for a report.
- When the server increments `report_finished`, it also asks the cache to remove any expired messages. I haven't done anything fancy here - the cache just iterates through all its entries, does an age check, and deletes them if they're expired. @tvst, I know you were potentially concerned about performance issues with the "iterate the whole cache" strategy. We could add a simple timer to this function to collect local metrics to see if it's actually an issue?
- Similarly, when the client receives a `report_finished` ForwardMsg, it performs the same cache expiration step. This means that the server and client's caches should stay in sync. (I haven't thought hard enough about whether it's possible for them to get briefly out of sync, but if they do, we have the new `/message` endpoint as a fallback.)
- If a report fails to run due to a compilation error, neither the server nor the client will increment the `report_run_count` for that session. (The run-count incrementing is conditional on the status value of the `report_finished` message, which is set to `FINISHED_WITH_COMPILE_ERROR` when that happens.)


There are client and server tests for all this new logic. But the easiest way to see the expiration in action is to run something like `examples/core/message_deduping.py` and watch the debug output on the server and the client. (You'll see logs for cache hits and misses - you should never see a miss! - on the client; and logs for sending cached message refs on the server.)
- This example just creates a big dataframe and sends it twice
- The first time the report is run, the message will only be delivered to the client once.
- If you rerun the report, the message won't be delivered at all because it'll be cached.
- If you remove the `st.dataframe()` calls and rerun the report, the dataframe will *not* be removed from the cache because it won't be old enough. Re-adding those calls and rerunning the report should confirm this.
- If you remove the dataframe calls and re-run the report _twice_ with them missing, they will then be expired from the cache. Re-adding them should result in the message being resent to the client.

* develop: (54 commits)
  Removing uber demo from streamlit repo (streamlit#159)
  Release 0.46.0 (streamlit#170)
  Magic fixes (streamlit#138)
  [docs] Add analytics; redirect /secret/docs; fix compilation problem (streamlit#149)
  Fix bug for startup under windows (streamlit#144)
  Responsive layout (streamlit#104)
  Add basic PR template
  Better method signatures (streamlit#88)
  Publish docs to both /docs and /secret/docs, until we deprecate /secret/docs in January. (streamlit#141)
  Rename/report2app (streamlit#126)
  Test running streamlit commands "bare" (streamlit#133)
  Updates to LP and sidebar. (streamlit#134)
  tests for z-index of date input popover in sidebar (streamlit#131)
  cypress test for escaping html in markdown (streamlit#125)
  On a Mac, check if xcode installed before requiring watchdog (streamlit#91)
  [Docs] Fix st.slider API in tutorial (streamlit#98)
  Sidebar exceptions (streamlit#107)
  Fixing unbound local variable (streamlit#110)
  Support hashing dataframes with unhashable objects. Gracefully f… (streamlit#118)
  Fix hashing if the object has a name but the name is not a string. (streamlit#117)
  ...