Update the contribution information and templates. The contribution information and templates were growing a bit stale, given that they haven't gotten a refresh since ~1.3.0. This commit reworks them to be more thorough and straightfoward.
Update general user-facing documentation in preperation for 2.0.0.
Update the licenses document to reflect that we do not use IndicatorFastScroll/MaterialDialogs anymore.
Add a proper readme and other documents for this project.
