ResetIndex step is yielded by greedy quantifier

If a greedy quantifier failed because it was forced to backtrack all the
way to the beginning, *and* it changed the engine's state, then yield a
ResetIndex step.
Fixed Lookahead's LookaroundStart index bug.

LookaroundStart had the raw, unmodified index of the lookaround engine,
instead of the lookaround's engine's index plus the modifier (which, for
LookAhead, is outerEngine.Index).
Add presentation mode via command line args (for Logitech presenter).
Merge branch 'feature/AlternationDisplayBug' into develop
Merge branch 'feature/CommandLineArgs' into develop