REORDER collapseTransitionsForwardFrom
REORDER removeStatesWithInDegree0
REORDER and SQUASH with future commit: WFA::equal()
ITrans: rename 'equal()' to 'equalIgnoringWeight()'

Because that's what it does, after all. :-)
Fix WFA::equal so that it removes the state from state_map too
Add inclusion guards
Move some WFA fixtures to header
WFA::removeStatesWithInDegree0: tests
WFA::clear(): fix bug with state removal.

Old version was removing states from a collection it was iterating over.
WFA::eraseState: fix memory bug I introduced a little bit ago

Original version didn't remove states from state_map. I didn't want this (keeping state_map and Q in sync) so I removed and deleted them. But that caused other problems, so now WFA stores separately a list of states it should delete on its destruction.

This is kind of bad that we have to do it this way, but I don't see any other alternative that keeps the 'state_map ~ Q' invariant I want and doesn't change everything.
Broken stuff for collapseEpsilonChains
Fix bug: it's possible to leave an empty TransSet in WFA::kpmap; compensate for this
Fix dumbest bug ever: increment wrong iterator
Fix last(?) bug in WFA::RemoveStatesWithInDegree0:

If there are no transitions to a state, we'd never notice that it doesn't have any because it wouldn't be added to the predecessors' data structure. Fix that.
Remove debugging output
Fix test cases for collapseEpsilonChains, which now passes
XFA::language_contains: Collapse epsilon chains
Revert "XFA containment generalization: build KeyedSemElemSets"

This reverts commit b3d9b5a4dfc30cf981443f67cc8bbd00b855d64f.

Conflicts:
	AddOns/Xfa/Source/wali/xfa/Xfa.cpp
Fixes for compiler errors one back
Re do the collapseEpsilonEdges transformation from a moment ago