add remove command (#73)

[keylime-unicorn]

Description

Added the 'remove' / 'rm' command for subreddits and 4chan boards. Allows users to remove subreddits and boards from their view.

Fixes #73

Type of change

New feature (non-breaking change which adds functionality)

[ginglis13]

Looks like tests are failing because of the autocomplete feature test. I just looked into it, and it's failing due to the toggling feature of autocomplete. The more I think abt it, the more i realize that the toggling of an autocompleted command (i.e. from sub -> subreddit, then subreddit -> sub) is not really a necessary feature to have because if the command 'subreddit' is already an input, there isn't really a reason to toggle back to input 'sub'.

To get around this we could remove the toggling feature altogether by getting rid of lines 23-25 in src/autocomplete.py and test 4 in tests/test_autocomplete.py. The other option would be to keep toggling and rework the autocomplete function.

@wtheisen @sambattalio

[wtheisen]

I've fixed the test and the autocomplete function but I pushed it into some branch that I have no idea where it is.