Added JTS library for triangulation and geometry-wise boolean operations

Allows polygons to be merged into (or substracted from) geometries,
which can be triangulated and used to clip arbitrary images.
JTS geometries can also be used for collision-detection using the JTS
"intersects" primitive.

The GeoTester class allows simple testing: left-click to merge polygons
via mouse, right-click to substract polygons.
Added support for pixmap-to-polygon, using a marching squares implementation from Bubble-Sets (IEEE TVCG 2009)

Refactored GeoTester
Included utility method, with defaults, to generate schema polygons
Merge pull request #211 from manuel-freire/pixmap-to-polygon

Pixmap to polygon