Fix install lbmpy without VCS

When copying lbmpy out of GIT it is not possible to install it because it can not determine its version. In fact, it is impossible to determine the version then. This MR tries to fix the situation.

added Bug label

requested review from @schottenhamml

assigned to @holzer

The solution provided here is one working possibility. Looking into NumPy to determine something like a "best practice" the solution is to just throw a RuntimeError: https://github.com/numpy/numpy/blob/main/setup.py#L45

Thus the question here is how to proceed @schottenhamml ?

Is there a good reason to allow to copy it without CVS? On the one hand, I would agree that as it is possible, it should be addressed. But on the other hand, as you mentioned in the warning, there could be some unwanted issues with the requirements there.

The warning would be an elegant solution for at least addressing the issue. However, I fear that users being users might ignore warnings and then wonder why they cannot install.

I think I would slightly vote for NumPy's solution but I don't have a super strong opinion.
Do you have any preferences, @holzer ?

Overall I would always prefer the NumPy way to do it because I kind of consider it a best practice. On the other side in this case it is a bit important to see that NumPy is a quasi-standard that is almost part of Python itself. Thus the situation that a user copies NumPy and tries to install it locally from a folder almost never occurs.

LbmPy is a lot different in this regard because it is quite common that internet access is limited on a cluster and so people will try other ways of installing. If we just remove this possibility it could be ugly for some people.

I fully agree with you on this one. However, in my opinion, it is not much of a difference whether one scps the downloaded zip file or clones the repo locally and then scps the repo (or a zipped version of it if it has to be faster).
But I definitely see your point and for the user it would be obviously more comfortable if the downloading just works. IF it works and does not break the environment...