pootle_store: Update the cache counts on Unit.delete()
pootle_store/caching: Get rid of old flag_for_deletion() calls
pootle_store: Move stringcount() to where it's locally used
pootle_translationproject: Add wordcount and suggestion_count cache
pootle_translationproject: Use database columns for counts
commands: Update refresh_stats to refresh translation projects
pootle_store: Always update the unit properly if its target has been updated
commands: Update quality checks in refresh_stats
cache: Get rid of an unnecessary deletefromcache call
signals: Fix unit_updated signal when there is no fuzzy unit
signals: Use direct count attributes instead of methods in unit_updated