Add FORD documentation (nearly) everywhere

[LeoTolstoi]

Heavily AI assisted documentation pass to add variable, function / subroutine and modules.

Notes:

• INTENT was added to several routines, necessitating a compile fix: 3b5af5b
• Auto-formatting pass was done, that is one PR 10 was deleted.
• I did not counter-check against the manual for all the formula due to time. Left that to the AI as well (it got fed the code and the manual).
• I did read through the changes, but, due to the amount of text & formula, I might have missed stuff.
• The code compiles and runs.
• Added to COMPILING.md that it is necessary to copy in the DLL files into the shetran.exe directory before it will run.
• Moved some parameter only modules to the "parameter" sub-directory for consistency in code organisation: 1e1813d