optimised source terms by removing unused variable and optimizing loops

Reference issue

Description

The changes are extracted from the branch tomawacBreakdep (as requiered from the review by Thierry). In psecific, the modifications are:

-removing the variable TSDER, for which calculation were done, but that were not used.

-optimizing some loops to prevent cache losses

-clean userFortran from the dean validation test, which was not used, but leaded to the validation to fail, because it contained one of the updated files

-changed some epsilon parameter in the Manche test case (the were only a few very small spots with differences)

I ran the validation using:

validate_telemac.py --report-name validation.csv -b --tags tomawac,-med

Checklist

All Merge Requests:

• Update NEWS.txt to describe your changes.
• Run compile_telemac.py --check to check FORTRAN coding conventions.
• Run pylint to check Python coding conventions.
• If you added new files, run compile_telemac.py --clean --rescan and commit the updated cmdf file(s) accordingly.
• Run compile_telemac.py --clean for both normal and debug configurations.
• Run validate_telemac.py for both normal and debug configurations.
• Run validate_telemac.py --notebook for both normal and debug configurations.
• Run doc_telemac.py if there are any modifications in the documentation.
• Run damocles.py --eficas if there are any modifications in the dictionaries.

In addition, for a new feature:

• Check that your feature works in both serial and parallel modes.
• Add at least one test case to check the functionality (with documentation, graphics and VnV script)
• Update the documentation for the module in which your feature will be available.