Matplotlib is required

[andreww]

While I remember, it seems that matplotlib is currently required to be installed (at least to run the atomistics command). For now I just installed it into the environment, but it looks like it's absence is worked around in some places. Ideally we should either add matplotlib to requirements.txt, or make sure all modules work around the absence of matplotlib in some way (even if things where it is really needed just exit with an error that says "install matplotlib you plonker".

[richetensor]

I'll just throw in a few additional workarounds to check that matplotlib is installed. It is probably better not to make it a requirement, as plotting is not really essential for users, just convenient, and pydis will continue to output text files that can be plotted using an external program. There is no need to heavily optimise plotting functions, so I'm quite happy liberally sprinkling the relevant sections of the code with try:...except:... statements.

[richetensor]

I have leavened the package with some try...except... statements. Let me know if any part of the code fails to run on your machine (with error messages attached, if possible).

[andreww]

Will do.

It struck me on the way home that this may be a case where a decorator for functions that need matplotlib would make things tidy. @needsmatplotlib or something for functions that need matplotlib and two (or three) lines at the top of each module.

[richetensor]

That could be a simple solution. I'll see what I can do.