Set up basic doc structure, and migrate information from STIX's GitHub wiki.
Create API doc structure. Probably needs some reworking/reduction for ideal structuring.
Added Likely_Impact. Closes #141.
Merge pull request #142 from STIXProject/issue_141

Added Likely_Impact. Closes #141.
Add 'Related Documentation' to the sidebar
Added pycharm .idea folder to gitignore
Fixed confidence typo in sightings
Merge remote-tracking branch 'origin/master' into walk
Fixed issue where ObjectProperties._parent caused duplication of yielded walk objects