Adding unit tests and TOX test environment with directory structure change
While adding TOX test environment and unit tests some small tweaks to main code were made to simplify unit testing and prepare easier future development. Directory structure changes according to comment in #4 (closed) and added few simple docs to start with. During the process package was renamed as well to mlx.warnings which is a bit more unique.
Once this pull request is accepted it should close #4 (closed)