The method was either returning true or throwing an exception, so it can
simply return void or throw an exception.

- separate data types for input arrays of binary operations
  (necessary for the equality comparison of two arrays of different
  type)
- added separate template parameter for ResultType, which defaults to
  the RealType
  (the goal is to allow sum of bool vectors into int instead of bool)

Added CWYGMRES solver (GMRES using Hauseholder orthogonalization and the compact CWY representation)