Feature request: ability to save more aspects of the EigenProblem at each point in a CriticalFinder.grid_generator scan

[afraser3]

CriticalFinder.grid_generator is fantastic for streamlining 2D EVP scans. But sometimes I want more than just the most-unstable eigenvalue at each point in the scan. Usually this is because I want the rest of the spectrum of eigenvalues, or sometimes even the full set of eigenvectors. In these cases, I've essentially coded up my own grid_generator with these added features I want specific to the project. But I've done this enough times now that it might make sense for this to be its own feature in eigentools.

I'm not exactly sure what this would look like. Maybe a couple flags like return_full_spectrum and return_eigenvectors, which would cause grid_generator to either return the corresponding arrays or save them to .h5 files? Once the machinery for eigenvectors/eigenvalues is implemented, it would be pretty easy for users to modify the source themselves if they want to get other information for more niche calculations, say if they wanted to condition number or L and M matrices or something.