- Fixed class extends by renaming the extended class and creating a n…

…ew one extending from the old in the same scope.

- We can now put proper modifications in the class extends node (they get elaboated in the correct scope).
- Only the toplevel class extends are expanded (not inherited). This bug will be fixed in a later commit.
- If the modifications on the extends node in the base class modifies the class we extend using class extends, those modifications will have higher priority. This is bug will be fixed in a later commit.


git-svn-id: https://openmodelica.org/svn/OpenModelica/trunk@4656 f25d12d1-65f4-0310-ae8a-bbce733d8d8e