Change style to PEP8

[MatthijsMars]

Currently the code is not written according to standard python conventions. (e.g. all classes are in lowercase, yet should be in CapWords) . However, this will probably break a lot of existing applications since the naming of basically all the classes will change, so maybe think about this (or add some aliases and a depreciation warning.

[Luke-Pratley]

@MatthijsMars I am happy to update some of the applications that use this code, it is not a huge problem. I think it is only a few at this point. The python version of s2inv would need to be updated most likely.