Add `karma delete` command.
Keep track of inverted links for term deletion.
Add class comment.
Refactor #modify to reduce complexity.
Refactor #check to reduce method complexity.
Add reverse link data on initial load.
Allow custom term patterns and normalization.
Update documentation on configuration.
Document the delete command.

Don't use a capture group in the multi word example pattern.
Require Lita ~> 2.6.
Reduce method complexity.
Delete reverse link data after deleting terming.
Bump version to 2.0.0.