Orthogonalisation

[JensWehner]

Should be in https://github.com/NLESC-JCER/spectra/tree/master/include/Spectra/LinAlg

The search space has to be orthogonalized using GS with twice is enough.

Depending on the datastructures of the search space and new testvectors.

It should be able to do two things:

a) Normailize the columns of a matrix with respect to each other
b) Normalize the columns of a matrix with respect to each other and the columns of another matrix, or a block of the same matrix.

The function should live in the Specta::Linalg directory

Needs to include tests