update ace-evaluator (download link + md5sum in cmake and make build systems): accept multilines comment at the beginning of potential.ace file
add first comment line for potentials/Cu-PBE-core-rep.ace
- update indentation to 2 characters
- remove dead code and unused class members
- use convenience functions in many places
- reuse code and members from Pair base class
- declare local functions/variables static
- PIMPL-ify access to the ACE evaluator library functions/classes
- correct settings member variables to match implementation
- no auto-download of user-pace src yet
- lib/pace/*.cpp,*.h are provided explicitly yet.
- implement CMake integration in USER-PACE.cmake and in CMakeLists.txt