Added a first fortran example to prove the tool works for fortran code

[LonelyCat124]

Added a first fortran example to prove it works.

Notably its a bit of a pain to compile with flang since by default it wants to use gfortran to actually compile, which by default will use libgomp and thus not work.

In the Makefile it then needs -L/path/to/llvm/lib setting in the LDFLAGS and then these are used to link to -lomp which means the llvm openMP is used.

I tested the example and it gives me the same output as the C version.

[adamtuft]

Hi Aidan,

Thank you very much for your contribution, I'll be happy to include it! For now, as Otter is a work-in-progress for my MSc, I want to keep separate my original work from any contributions to ensure I do not submit your contributions as my own. Are you happy for me to merge your PR into a separate branch for now, to be merged into main once I have submitted?

[adamtuft]

I have created the contributions branch for this purpose.

[LonelyCat124]

Sure thing, I'll update this PR to merge to that branch - probably we can hold this PR off as I'll probably put together a few more of the examples to check it works for other parts as well.

[adamtuft]

Now that I've tagged my submission version I can accept your pull request, but I think you will need to rebase onto dev first (either that, or perhaps I should rebase contributions onto dev - although I'm not sure what this would do to your PR).