New design for Model classes based around strings for specifying different operators and states.
Restored previous Model class interface for backwards compatibility.
Updated SpinOne model to use new Model class design.
Added OptSet argument to Model::op method. Changed MPSt constructor taking InitState argument to get Model reference from initState instead of providing explicitly. Updated sandbox/sample codes and unit tests accordingly.

Conflicts:
	sample/dmrgj1j2.cc
	sandbox/dmrgj1j2.cc
Deprecated but preserved older MPSt InitState constructor for backwards compatibility.
Fixed some compilation errors arising from conflicts with new and old interfaces to Model and InitState.
Added alternative names for SpinOne states and x eigenstates to SpinOne op method.
Finished converting models to new string-based interface. Converted hams/HubbardChain.h to this new usage.
Fixed typo in localmpo unit test.
Merge branch 'stringmod': new interface for Model classes taking string arguments. Old interface still supported for backwards compatibility.
Added default implementations of new private Model methods to support older user-defined Model subclasses.
Replaced conj(T) template in index.h with explicit overloads; was conflicting with conj template defined for std::complex when using icpc compiler.
Added numLeft() methods to Combiner and IQCombiner to help unify interface.
Improved denmatDecomp logic to correctly identify active indices in more cases.
Fixed bug where dat.solo() not being called for non-const IQTensor methods scaleOutNorm and scaleTo.
Changed out deprecated rl() method for numLeft().
Found and fixed major bug in addition of complex ITensors, triggered for a+b when a real, b complex, and a and b have different Index order. Fixes #45. Wrote some related unit tests. Also simplified handling of complex ITensors in expandIndex and updated unittest/mps_test.cc to use latest InitState interface.
Changed deprecated index_in_common method to use warnDeprecated method.
Added template method uniqueIndex which is the opposite of commonIndex.
Converted certain psiHphi and psiHKphi methods to templates over the tensor type.