Code style (PEP8 and more)

[Ball-Man]

Conformed code to existing guidelines, in particular:

• line length, suggested by PEP8 (79 max)
• empty line after class docstrings, suggested by PEP257

Moreover, identity operator is is now used instead of equality comparison == for type checks (used in remove_processor, get_processor). When comparing types, this is semantically equivalent and should be generally faster.

[benmoran56]

Thank you for the pull request.

I should have mentioned in the README, but style guide is basically "PEP8, except for strict line length limits. This only applies to the code, not the comments. Is it possible to revert only the line wrapping for code segments only? The other changes all look good.

[Ball-Man]

No problem at all

[benmoran56]

Thank you very much!