Cache invalidation of categories (or in general mm_relations)
When editing a record the page cache is automatically flush by tags like
tt_content[record:uid] or tt_address[record:uid]
When i add or remove a record from/to a sys_category this is an indirect change of the sys_category.
I would except that the cache is flushed for the sys_category too.
Can we integrate it? Maybe via a feature-flag?