Backwards-incompatible changes

• Bleach markdown (now that safe_mode isn't available any more)
• Use a different markdown renderer for pages and user-generated content (as the security profile of the two is different).
• Display talk list in a table.
• Emit frab-compatible pentabarf.xml

Minor

• Optimize talk pages.
• Translation updates.
• Translation compilation is now checked in CI.
• Make talk review scores the same in admin and model.

New Settings:

• WAFER_CONFERENCE_ACRONYM: The short name of the conference, used in the pentabarf XML schedule.
• WAFER_PAGE_MARKITUP_FILTER: The markitup filter to use for pages, not user-generated content.