This adds synsets from the Open Multilingual WordNet as a valid form of `node` or `rel`! The format is `XXXXXXXX-Y` where `XXXXXXXX` is an 8 digit code and `Y` is a letter corresponding to a part of speech (n, v, a, r).
Here are all the big changes:
- davar now downloads both wordnet and omw from nltk to `./nltk_data` on init
- `Node` and `Rel` refactored into `WikidataItem(Node)` and `WikidataProperty(Rel)`
- `Node` and `Rel` now both inherit from `DavarWord` which stores shared code
- `DavarWord` refactored to use full strings as `id`s
- `DavarWord`s now validate their ids with regex on init
- documentation tweaked + improved
- tests updated to cover new features
<div title="I was going to call this release OMWFTW before I realized that it is not, in fact, 2012.">☻</div>