Fix misplaced gamemodes in tests
Let spawners and AI pick leaders from different levels occasionally
Extend the difficulty hp scaling to spawners
Use difficulty setting for non-UI tests, too
Add lescape that tells if the level has an escape feature on it

Not secret, because known from the Caves part of game ModeKind.
Seek and trigger escape only after all else explored
Get rid of the special Caves definitions for test runs

They are no longer needed now that AI does not escape ASAP.
Don't let AI push friends through stairs
Simplify bwait; it's not compositional any more, but accurate
Improve target retention and targeting escapes
Fix wrong target for non-moving actor in melee range of foes