Major tidy up of current code base

[cnluzon]

Now that there was some base testing for the main functionality, it's good to clean up the code.

Things to be done:

• [x] Reorder functions to a meaningful order: Public first, then relevance order.
• [x] Went through documentation and explained further functionality and parameters.
• [x] Added as many @inheritParams as possible centralize parameter description and avoid repetitive documentation.
• [x] Tidy up bwtools code (mostly complying to tidyverse style guide).
• [x] Tidy up bwplot code.
• [x] Tidy up test files code.