- task: make filter tag case-insensitive

- task: unify head html output (in _search.inc)

Made exact/max size setting more robust.
Gallery filter now deletes affected caches when defaults change.

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.

and used the hack in #121306 to do the same for the Gallery2 admin sitebar
(off by default).
- Fixed up the handling of exactsize and maxsize.
- Added form validation for sizes (and sidebar settings).
- (Hopefully) fixed small bug in filter where n param was ignored.

- task: small cleanup of theme function in blocks code
- bugfix: pager, edit G2 link, ... on user status page

- task: added exactsize option for search
- feature: simple report generator (to assist with bug reports)
- bugfix: support for piped arguments in filter tags
- bugfix: several issues with 'Site Admin' group <> 'admin' role sync feature
- bugfix: add code to handle admin user (uid=1) properly after install
- many minor bugfixes

- 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)