`Matrix::orthogonalize()` works only for distributed case.

[dreamer2368]

Based on the definition in lib/linalg/Matrix.cpp, void Matrix::orthogonalize() works only when the matrix is distributed (in parallel case). It should have a line:

CAROM_VERIFY(distributed());

[cval26]

@dreamer2368 Can you elaborate on this?

I'm working on PR #239 which solves a bug in the orthogonalize() method and adds an incremental method orthogonalize_last(). The PR also includes unit tests for those methods which run successfully for non-distributed matrices.

Do those changes solve the issue you're referring to here?