Bump version number to 0.3.0
Add option to remove empty subdirectories

The RemoveEmpty option (default: true) will remove empty subdirectories
from monitored paths.
Move options into a dict

This makes it easier to add new options in the future.
Create trash directory if it does not exist
Add mypy and typing information
Update systemd files to use a timer
Use pathlib in test
Remove unused test configuration file
Bump version number to v0.2.1
Coerce the Shred option into a boolean
Bump version numbero v0.2.0
Use pathlib for path operations
Update minimum Python version to 3.5
Add pipx instructions to README
Mild refactoring to improve pylint score
Remove optional arguments from sweep()