Read the graph inline, so that the target travels with the Makefile it
describes and can be lifted into another project by copying two rules.

The script had drifted from the copy kept as a sample elsewhere, which
had meanwhile learned to name the makefile it reads rather than assume
it. Both now hold the same rules, and correctness no longer rests on the
file happening to be called Makefile.

- Move the pipeline and the awk into the recipe, dropping
  scripts/make-target-map.sh
- Add MAKEFILE, so `-f` and the self-filter both name the file make read
- Read the help text out of MAKEFILE_LIST, covering included fragments
- Separate a description from its target with a tab

Convert the 'map' target in the Makefile to a native in-line, dropping the external script

This makes the text in dialog immediate complete readable, without scrolling.

Consolidated "The underlying task failed:", the task description, failure reason, and return code into one compact block (single newlines) instead of separate blank-line-separated paragraphs, while keeping one blank line before/after the block for readability.

Reading the list in again after a checkout puts the scroll back at the
top and drops the selection with it, and putting that selection back
left the commit the list had just moved to below the fold, so changing
branch looked like nothing had happened at all.

* Bring a restored selection into view, the way the re-selection it
  replaced used to
* Leave the list where it stands when the selection was never dropped,
  so an update on its own still cannot move it under the user

Remove CI messages

Remove empty lines in dialog

…h-tip

Fix a branch checkout leaving its tip off screen