Put in a check to get out of an infinite loop in davidson.

Renamed template argument (LocalT to BigMatrixT) in davidson
to make clear that this is the big matrix that davidson works on.

Added some error checks.
Removed redundant size() method from IndexSet (just use r() instead).
Removed a few unused or redundant methods from IndexSet and QN.
More info in a div error printout
Changed name of argument in checkQNs for an MPO
Fixed minor issue where IQCombiner wasn't auto-determining arrows properly.
Improved printout of QNs in IQTensor (added commas in between).
Replaced some MPOt overloads with simple calls to the parent (MPSt) method with an addition Opt. Changed MPSt::orthogonalize to reset orthogonality bounds before calling position(N). Renamed the confusing addNoOrth to addAssumeOrth.
Merging Steve's latest changes into my repo.
Cleanup of some debugging code.