Changed sets to take jts geometry in constructor
Renamed XXSet to MultiXX
Merge remote-tracking branch 'upstream/master' into feature/feature
Added Feature classes.

 - Renamed OneDimensions to OneDimension.
 - Made GeometryCollection extend Geometry
 - Methods that apply to Geometries excluding GeometryCollection are now in
   Relatable trait.
 - Implemented some predicates e.g. covers, coveredBy
Renamed geom to jtsGeom.

Now that Feature has a geom, this makes it clearer that the
jtsGeom is the internally wrapped jts geometry.
Removed MultiGeometry
Merge pull request #752 from lossyrob/feature/feature

Add Feature classes to geotrellis.feature