annotate: temporarily change version to 2.19

This is to force compilation with current version.
The snippet doesn't run with 2.16.2 or 2.17.3
2.17.27 however does work.

The offending code is in props-alist.
If I replace its body with (list 1 2 3)
(and of course comment any use of the resulting list)
everything works fine, so it isn't because of the
calling convention with \with
(although the error message suggests this).
annotate: update example containing a line break

Add a line break to a string command
annotate: Getting to grips with string arguments

Now the function produces a alist of the context mods.
Currently they are printed to the console. This functionality
will remain part of the game as one possible output target,
currently it's more a test case.

Additionally the file now contains an outline of TODOs