Wrap long command descriptions at 80 chars
Add open command

* Open accepts a mutually exclusive list of indices or tags and opens
  them using `xdg-open`, or with the command specified in the config
* Update config with new `browser` option.
* Refactor Filter to include indices.
Use default config for `doc` command (fix #8)
Initial commit

* Add add, list, and remove
* Add doc generation (bmk doc)
* Add Makefile