Add changes made to reach lspr application
* Ported PyGBe to Python 3 (!!!). This breaks Python 2 support, but who cares.
* Better regression tests (faster, anyway) using pytest
+* Localized Surface Plasmon Resonance application:
+
+ #### Added:
+ - lspr main function to run this applications separately.
+ - lspr application's examples to the `examples` folder.
+ - Regression and convergence tests for the examples added.
+ - Update documentation with new application to github pages
+
+ #### Changed:
+ - GMRES function to accept complex numbers. Changed based on `gmres_mgs`
+ from PyAMG, where modified Gram-Schmidt is used to orthogonalize the
+ Krylov Space and Givens Rotations are used to provide the residual
+ norm each iteration
+ - If complex dielectric, the matvec calls the tree code
+ separately with the Real part and Imaginary part of the solution and
+ multiplies by complex constant afterwards. This prevents to modify the
+ treecode to accept complex numbers.
+ - Add to RHS functions the corresponding terms to solve lspr problems.
### Changed
