ITensor version v1.0.0

This release adds a number of new features and makes some overdue breaking changes to the library. For detailed information, view the change log. Some notable changes include: Put all code into namespace itensor No more dependence on boost library when compiling with USE_CPP11=yes set in options.mk. Minimal boost header code included with library download when compiling with USE_CPP11=no. Removed ITSparse and IQTSparse classes. Now ITensor carry an internal sparse-mode flag. MPS class no longer stores accuracy parameters (maxm,cutoff,...) or a vector of Spectrum objects. MPS class no longer defines + and += operators. Use functions sum and plusEq instead. Improved methods for constructing OptSet named argument sets