Simplify Cli Structure

[arcanearronax]

This change removes the need to parse arguments from sys.argv by using Click in order to handle the command line arguments. The flags that can be used have been modified a bit to support this change.

• --ignore/-i This is used to identify which file extensions to ignore when sorting.
• --sched/-s This is used to schedule sorting.
• --desched/-d This is used to deschedule sorting.
• --undosort/-u This is used to undo a sort.
• -h This is used to display the different command line arguments available and usage.

One notable change to usage is that the extensions to ignore during sorting can be passed with or without the preceding period, multiple --ignore/-i flags can be used to pass multiple extensions (a comma delimited string of extensions can still be passed), and the parsing of extensions is handled in a more pythonic way.