Partial work on implementing new SVDWorker::diagonalize method.
Added unit test for HermitianEigenvalues method.
Moved truncation code from ITensor svdRank2 and diag_hermitian into a single function called trunctate. Worked on complex support for diag_hermitian.
Split IQTensor truncation code into a separate function.
Fixed arrow bug in diag_hermitian and put in an error message for incorrect arrow directions.
Fixed diagonalization of complex tensors and wrote a related unit test.
Merge branch 'diagonalize' into 'master'