Algorithmic roadmap

[haampie]

Open issues:

• [x] Deflation
  • [x] Early locking (#71) --- implemented via Krylov-Schur
  • [x] Purging / removing eigenvalues that are unwanted (http://www.netlib.org/utk/people/JackDongarra/etemplates/node232.html). Plus: determining if an eigenvalue is unwanted (#80) --- implemented via Krylov-Schur
• [x] Reordering of the Schur form such that eigenvalues closest to the specified target appear first (more or less covered by #71)
• [ ] B-inner product for generalized problems (#50)
• [ ] Tricks: improve eigenvector approximation in certain spectral transformations (http://www.netlib.org/utk/people/JackDongarra/etemplates/node233.html)

Finished:

• [x] Handle close-to-0 eigenvalue better; stopping criterion is probably to strict for them now. (#72)