B001 ModelicaSystem split

[syntron]

(B001) split ModelicaSystem

[ModelicaSystem] split ModelicaSystem into ModelicaSystemABC and ModelicaSystem
[ModelicaSystem] rename ModelicaSystem => ModelicaSystemOMC
* add compatibility variable for ModelicaSystem
[test_ModelicaSystemOMC] rename from ModelicaSystem and update
[test_*] use ModelicaSystemOMC
[ModelicaSystem*] fix last usages of ModelicaSystem() in comments & docstrings

[adeas31]

[ModelicaSystem] split ModelicaSystem into ModelicaSystemABC and ModelicaSystem

[ModelicaSystem] rename ModelicaSystem => ModelicaSystemOMC

We could do ModelicaSystemBase instead of ModelicaSystemABC and ModelicaSystem instead of ModelicaSystemOMC. This requires less changes both in the code base and for the users.

[syntron]

[ModelicaSystem] split ModelicaSystem into ModelicaSystemABC and ModelicaSystem

[ModelicaSystem] rename ModelicaSystem => ModelicaSystemOMC

We could do ModelicaSystemBase instead of ModelicaSystemABC and ModelicaSystem instead of ModelicaSystemOMC. This requires less changes both in the code base and for the users.

This is done on purpose; a later change (PR #437) creates a compatibility layer => ModelicaSystem is used there.

*ABC is used to indicate an uncomplete class => there are functions missing which are just added in the derived classes *OMC or *Runner. This is handled for ModelicaSystem*, OM(C)Session* and Modelica(System)DoE*. See PR #441, PR #442 and PR #443.

[adeas31]

Resolve conflicts.

[syntron]

Resolve conflicts.

@adeas31 Done ...

[syntron]

@adeas31 anything I can do here? the pull request is fine - it is just a timeout for Windows build ...