New meta issue to track and collect all the information about the going BCL size reduction work.

Relevant PR's:

• Allow some Globalization code to be dynamically removed. #596 - there is a lot of interesting discussion in here.

• Add option to the XML input to rewrite methods to throw / stubs. #555 - this was a proposal that was abandoned.

• Add custom logic for reflection-emit to RemoveFeaturesStep. #590 - this is the technique that we're currently using to dynamically remove the System.Reflection.Emit code, which will shortly also be used for some globalization stuff.

• For Globalization (Japanese, Taiwan and Hebrew Calendars): Make DateTimeFormatInfo and DateTimeParse more linker friendly. mono/corefx#298, Make CalendarData more linker friendly. mono/mono#14825, Allow some Globalization code to be dynamically removed. #596, Bump CoreFX to pickup https://github.com/mono/corefx/pull/298. mono/mono#14851.

• Interesting design discussion: Add Link-time framework feature removal spec designs#42.

• Upstreaming and discussing with CoreFX: Disable some Calendars when using GlobalizationMode.Invariant. corefx#38281.

I will continually update this issue and document things in here while we move forward.