Tab completion

[joereynolds]

We'll want tab completion in jn.

At a minimum we'll want

• All of the possible commands in their long form
  • cat
  • config
  • edit
  • grep
  • etc...
• All of our books

Since the books are stored in a configurable location, we'll need to read these out from our config when we <tab>.
So, in our bash completion we'll have to grep XDG_CONFIG_HOME/jn/config.ini for notes_location (without a ; at the start).

This will be the dir that contains all of our books that we can add to the completion list