Modernising the code

This issue lists several steps that should lead to a more modern TELEMAC codebase.

• Move all Fortran code from the old Fortran 77 fixed-format style to Fortran 90 free format
• Replace TELEMAC Python-based homemade build system with CMake
• Apply modern Fortran coding conventions that should be specified in the Developer Guide
• Replace Fortran Doxygen documentation with a documentation system more suited to Fortran
• Replace F2PY with another system to generate Python wrappers
• Apply PEP 8 coding conventions to all Python files
• Replace Python Doxygen documentation with Sphinx, which is more suited to Python

Edit (Nov 5, 2025): Doxygen will remain in use for the time being; a lot of work has been done to format Doxygen comments properly in MR !279 (merged), and for this reason there are no plans to switch to FORD in the near future.