Defined macro Array as boost::array to avoid any ambiguity with std::array.
Added diag() method for getting diagonal elements of an ITensor. Wrote a unit test.
Fixed indexset_test.cc to compile with std library providing shared_ptr. Added helpful output to matrix_test.
Added fitApplyMPO and applyExpH (which also uses fitting) methods to mpo.h/cc.
Added swap method to MPSt class.
Changed imagTEvol implementation to use new applyExpH method.
Switched imagTEvol back to using fitApplyMPO for now, since applyExpH has a tricky arrows bug. svd method now recognizes DoRelCutoff Opt.
Changed prodstats.h timer feature to use std::chrono and split into a separate Timers class.
Added timers to imagTEvol and fitApplyMPO.