Merge topic 'KateImprovements'

e7f7bff4f5 Kate: improve the way the VCS-specific files are searched
96389b4cd3 Kate: add support for hg and fossil
4c32623f5f Help: fix typo in docs for set_property()
9a7612d2d0 Kate: make it possible to force a mode for the "files" entry
8a7aa2642b Help: add documentation for Kate-related variable

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !8154