Replaced type names OptSet and Opt by Args everywhere.
Added comment to check on sign of eigs in diag_hermitian
Improved some MPS and MPO addition code that was failing for summing Hamiltonian terms for large 2d systems. Most likely problem was the absence of the DoRelCutoff=true option in MPOt::addAssumeOrth.
Improved itensor::printf to always immediately flush buffer.
Fixed IQTensor svd and denmatDecomp to include QNs in returned Spectrum object. Thanks to Maciej Koch-Janusz for pointing out this bug.