* There was a use of target_link_directories instead of target_include_directories.
* Executable targets were available but could not be compiled without its library.
* Dune dependencies are taken directly from its global variables. This enables MPI and UG_PARALLEL when necessary.
* The options file expected CMAKE_FLAGS and MAKE_FLAGS from environment, but dune-common happens to clear them before calling the options file. On this version, these are replaced by CMAKE_OPTIONS and MAKE_OPTIONS

The multidomain-lib and singledomain-lib are too generic to be set in any system, so this is replaced for something more specific

* This is header is removed for 2.8 and higher, tough

This makes more sensible name choices for exported target names, it manages installation components and fixes the test stage in CI 

* 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.