Core: "Pythonification" of bindings

[GPMueller]

Currently, the Python bindings are not only inconsistent, but also largely follow bad naming practices! See https://www.python.org/dev/peps/pep-0008/#naming-conventions Since we are already inconsistent, at some point the entire bindings should be straightened out and made consistent with the recommended standard.

Specifically:

• Modules should have short, all-lowercase names. Underscores can be used in the module name if it improves readability. Python packages should also have short, all-lowercase names, although the use of underscores is discouraged.
• Class names should normally use the CapWords convention (CapitalizedWords)
• Function names should be lowercase, with words separated by underscores as necessary to improve readability.

[GPMueller]

Pythonified the spirit.constants module with 9152df3ace521dc2d2029d9fc1e778480dee1381 by turning the functions into module constants.

[GPMueller]

Pythonified the remaining bindings with 3c8288a20a9a5bbf3e4c9f102172e8fc54b79c1d on feature-improved-api.

[GPMueller]

Merged into develop with eb841c5bd39941d4c437895845969c00ff224f10.