Rename ZZ9000Test -> ZZ9000OS in documentation

This was renamed in the source tree a while ago,
adjust documentation.

Hide hardware sprite if video capture (scandoubler) is enabled, show hardware sprite if it is currently disabled.

Results in some amount of code duplication, but also a decent speedup by skipping calculations and comparisons not needed in each mode.

In theory, this works. In practice, I can't currently find a way to test it.

This may or may not require P96 2.4.3 to function correctly for some operations.

This one is a bit tricky. It appears to work perfectly fine, but there's currently no easy way to test that all the minterm modes come out looking the way they should, as even the Planar2Direct P96 test pre-handles these in software.
Scrollbars in Directory Opus look fine though, as does everything else I could find, so that is probably a good sign.

Requires the changes from the z3-c2p-experiment branch on drivers.