This also makes the first baby steps towards a sound treatment of
higher-order kinds (type type int).
Adds test cases showcasing the new features.
* Also fixes breakage after the rebase
* fix the usage of unresolved static[T] parameters in proc signatures
* fix tsametype and tmacrogenerics
* Allow creating composite type classes with concepts and using them in type signatures
* Allow integers to be used in ident concatenations
* Support using imported C++ generic types in proc signatures
* fixes#7230
* closes#7379
* re-enable some metatype tests
* hangle static generic params when used in the importcpp pragma
* importcpp works for generic types with fields; fixes#6415
* revert a too agressive safety check that ended up breaking the tests
