Use program/end program for main programme in Mistra

[pb866]

In str.f, we should include a program str / end program str statement to make it clearer, where the main programme starts/end. Also, it is not quite clear, why the file is called str and we should consider to rename the file main routine to mistra.

[JosueBock]

I agree that both changes would be fine, however much broader changes must be made in this file, so I will leave it for the moment (it will also require to update the manual, while at the moment it is consistent with the current model structure)

[rs028]

@JosueBock Can you open an issue with more information on the broader changes that need to be made to str.f, please? (Also in reference to point 4 of issue #2).

[JosueBock]

Main program has been explicitly identified using program / end program, and named "mistra"
See this commit : 7154573