Markdown reformatting
Fix tag filtering (do not inherit tag privacy tags!)

Also:
* Make :cat_image_privacy (and :tag_tag_private) actually optional
* Expand filtering description in config.md
Create a gallery v0 testing snapshot.
Trash tags and categories tables as well in gallery 0-to-1 migration.

Also:
* Create a gallery v0 testing snapshot w/ integration test.
* Change destination name for
* Bugfix in SQL script splitting.
Merge branch 'fix-v0-v1-migr'