Control variables are clasified in a module when they appear in a view as a model variable

[enekomartinmartinez]

The control variables (TIME STEP, INITIAL TIME, FINAL TIME, SAVEPER) are classified in a module when they appear in that view as a model variable and the model translation is split by views. This provokes a crash during model loading.

We should define their values always in the main file filtering the variables.

We should also include a warning for control variables when they are defined in a view or for those regular variables that are defined in more than one view.

[enekomartinmartinez]

Solved in branch views. I will open a PR soon.