Docs on Vectorizable and Targetable
fixes for Vectorizable/Targetable docs
DX, DP, dL documentation
slightly more verbose menpo package landing page
Merge pull request #356 from jabooth/docs

Vectorizable, Targetable, DX, DP, DL documentation.
HOTFIX: set correct group label on a landmarkgroup
Merge remote-tracking branch 'upstream/master'