Clean-up of code

[kallewesterling]

• [x] Format all code with black.
• [x] Correct spellings/singulars where plurals should be used.
• [x] Structure imports + remove unnecessary ones.
• [x] Remove references to rosa's home directory.
• [x] Remove unnecessary keywords = [].
• [x] Remove deprecated code.
• [x] Clean up documentation (although this calls for a more extensive issue opened with more)
• [x] Drop the u"" string syntax. (The package requires Python 3.x, where all strings are already unicoded for convenience)