Drop problematic global text caching

The trouble is that there is a bazillions of settings/options/conditions that may affect text filter outcomes - it is technically not possible to do a high performance caching at this level.

Dropping the global text caching will fix multitude of issues at the same time:

• JS handling
• use of PAGE and OUTPUT
• use of any other globals
• easier resetting of local filter caches
• etc.

There are already static caches in most filters, which means this should not cause perf regressions on large sites - they were supposed to turn off this ugly feature already...

The next step is to migrate individual filter caches to MUC (unless the perf overhead of MUC