Splitted AugRie header in implementation files

Moved all implementation details in separate implementation files.
Splitted vectorized and non-vec implementation.
Refactoring for readability

- restructured public and private areas
- reordered vectorized and non vectorized regions to reduce the
number of #ifdefs
- reordered initialization and declaration of members to fix
the reorder problem
Fixed warnings to compile with -Werror
Changed parentheses to match the vector version
Changend inheritance to composition

Skipped the inheritance of the vectorized augrie solver.
For the scalar case, a simple augrie solver has been added instead.
Minor fix in the comments
Decomposed AugRie solver in header and impl-file

- splitted declarations and definitions
- removed everything, that was commented out for the last two years