Feature project - adding additional methods to the JTS wrapper 

Implemented:

-vertices/getCoordinates - didn't do this for Point as it seemed trivial
-envelope/bounding box - didn't do this for Point as it seemed trivial
-length/perimeter - getLength calculates the length of a line or the perimeter of a polygon, so I named them accordingly. Point is always 0, so I left it out.
-isSimple - just for lines. Points can't self-intersect, and neither can valid polygons
-overlaps - only valid for geometries with same dimensions
-symDifference -  point, line, and polygon

** I haven't added any of the above methods to the Sets or GC yet. Waiting to discuss with @lossyrob where it makes sense to add them.