This also fixes a long-standing off-by-one with the generated ObsRows:
Before this commit, the game would (upon F11) eat every black pixel from
the map template that was directly left of a white pixel, eg.
#### ## # ## ... would become
### # # ...
GENERATED MAPS ARE NOW DIFFERENT!
With this bug gone, dumping obs (F8) and loading that back in as a map
template (F11) should now be fully round-trip compatible and not lose
pixels anymore.
Extra feature:
(R>=200, G in [128..199], B>=200) in the map template now designate zones
that should not be obstructed but also not generate border rocks when
skinned (F12). Makes editing energy temple styled maps much easier since
we don't have to manually erase tiles on layer "5" anymore, all the time.
