* This changes allow to import and use targets by just finding the dune-copasi library. No dune library required for downstream project.
* The testing library may be used as a subfolder or as a dune-copasi downstream project.
* The config file is installed so that non-dune users may just include the config definitions without re-generation of the file.
* Python project not setup. It is not doing anything anyways.
* Updated dune module requirements to 2.7
* Adds basic information for CMake packaging

Now targets seem to be importable in a very simple manner.

* Library modes can be switched by default in CMake with the option BUILD_SHARED_LIBS
  hence no need to hardcode them with different targets.
* Exported targets were not working properly because the config file didn't contain enough
  information (DUNE creates one by default). So I remove it and will refactor all CMakeFiles
  later to use modern CMake directly (without DUNE macros).