doc: termios defaults. ref #6992
doc: :help shell-powershell
doc: provider: Python minimum version is 2.7, 3.4
doc: remove :!start special-case. #5844
doc: mention #7917 change which accepts empty Array for Dictionary parameter
doc: <Cmd> pseudokey
doc: lmap change #5658
doc: -s, -es

- move to api.txt
- rewrite

Problem:    When calling setpos() with a buffer argument it often is ignored.
            (Matthew Malcomson)
Solution:   Make the buffer argument work for all marks local to a buffer.
            (neovim vim/vim#5713)  Add more tests.
https://github.com/vim/vim/commit/f13e00b2cf381e13fd327b5387a5bd6f004ac2a3

Fixes 2 failing tests in startup_spec.lua.

The Windows-only `--literal` option complicates support of "stdin-as-text
+ file-args" (#7679).  Could work around it, but it's not worth
the trouble:
- users have a reasonable (and englightening) alternative: nvim +"n *"
- "always literal" is more consistent/predictable
- avoids platform-specific special-case

Unrelated changes:
- Replace fileno(stdxx) with STDXX_FILENO for consistency (not motivated
  by any observed technical reason).

Problem:    Character classes are not well tested. They can differ between
            platforms.
Solution:   Add tests.  In the documentation make clear which classes depend
            on what library function.  Only use :cntrl: and :graph: for ASCII.
            (Kazunobu Kuriyama, Dominique Pelle, closes vim/vim#1560)
            Update the documentation.
https://github.com/vim/vim/commit/0c078fc7db2902d4ccba04506db082ddbef45a8c

Also rename changedtick -> changedtick_event