- bugfix: Wrong images displayed when adding with [G2] tag (#148873)
- bugfix: G2Image gallery path not being set (#148872)
- bugfix: G2Image not adhering to the Default Action setting (#148869)

Used coder to try to clean up code standard (except for the G2 camelCase of
course). A painful exercise! Hopefully I didn't break anything.

- task: rework of G2 filter code
- feature: simple regexp for language codes
- many small bugfixes and cleanup

- improved user/role sync (incl. batch import/export of users)
- tabbed configuration screens
- better debugging options
- gallery_menu module (link to G2 albums from the menu)