Add STORMPY_prefix to CMake

[volkm]

Add STORMPY_Xprefix to CMake options. Helps with distinguishing from Storm CMake options.

Will maybe require an adaption in PAYNT as well.

[sjunges]

Great. I just wondered whether STORMPY_CARL_DIR_HINT or STORMPY_STORM_DIR_HINT is the right way? Should this not be just STORM_DIR_HINT?

[volkm]

I agree that it looks a bit weird. I had two main thoughts:

• if everything starts with STORMPY.. it is easier to see what CMake options are relevant for stormpy
• we avoid a possible name clash with another tool (or Storm itself) which could have a similar option STORM_DIR_HINT. For instance, PAYNT could use similar variables.

But I have no strong opinion and could also implement your suggestion.

[sjunges]

I think it is a good idea, my main frustration would be if I would need to set STORMPY_STORM_DIR_HINT=... PAYNT_STORM_DIR_HINT=...

[volkm]

I can understand it.
@TheGreatfpmK Do you have an opinion from the PAYNT side?