[bugfix] Cleanup of AMG constructors
Summary
Several constructors in AMG preconditioners can not work and when instantiated give compiler errors. This is corrected in the MR.
Details
- Fixed mutable vs. const OperatorHierarchy argument in AMG, FastAMG, and KAMG
- Removed nonexisting constructor-calls in KAMG
This fixes #75 (closed)
Note: Two (deprecated) constructors in KAMG are removed completely, since the initialization of the underlying AMG object with the given parameters is not possible, i.e. no corresponding AMG constructor is available.