And document which aprts are still missing.
The keyword list is are copied from make_pot.sh.
Sorting by file helps keeping future PO(T) update diffs small'ish
and is also done in wangqr’s PO-file update procedure. (POT file
generation also sorts, but by preapplying `LC_ALL=C sort` to the
file list instead of using xgettext’s sorting option.)
Without this, meson’s aegisub-pot missed the majority of translatable
strings from C++ sources. While this brings the target much closerto
make_pot.sh, the remaining strings aren't straigthforward to integrate
unfortunately. At the time of writing meson has no support for iss files
and make_pot.sh uses custom logic to select only specific strings
from Lua and JSON files.
Even after this commit, POT updates should
thus still continue to use make_pot.sh.
