Though these are not as user-facing as other strings, the action names
still are somewhat user-facing. Let's rename them consistently with the
GUI and the API.
This commit also handles user config migration so that custom shortcuts
are not lost.
...to path.
Changes the names of
gimp_vectors_* () API to
gimp_path[s]_* (). Renames related files
to [path] instead of [vectors], along with
relevant enums and functions.