* Added a collection of simple fortran codes that are used for testing.

* Added automatic tests for each new case added there.
* Moved tests from unittest to pytest.
* Fixed old failing tests.
* Fixed some issues that arose when trying to use ImplementRPE with simple dummy codes: Where to add the additional use rp_emulator.
* Added an extra pre-processing step to replace all variable definitions that used the traditional style (without ::).