Add ST_3DLength

Note 1: PostGIS does not allow ST_3DLength to take a Polygon as a
parameter. For this purpose, a PostGIS user must use ST_Perimeter, which
was not implemented in GDMS.

Note 2: PostGIS also allows MutliLineStrings (for ST_3DLength) and
MultiPolygons (for ST_Perimeter), while GDMS only allowed for
LineStrings and Polygons.
Rename CoordinateUtils
Add ST_CoordDim
Add ST_CircleCompacity
Use a simpler method for testing for geometry type
Clean up javadoc / Add test tag
Add tests for geometry collections
Rename ST_CircleCompacity -> ST_CompactnessRatio

Note that the definition given in
http://www.spatialanalysisonline.com/HTML/?shape.htm is equivalent to
the previous definition (in ST_CircleCompacity).
Add a test for a 3D geometry
Make ST_3DLength return 2D length for 2D geoms.

Before, ST_3DLength was returning 0 for a 2D geometry, which didn't make
any sense. Now it returns the same value as ST_Length for 2D geometries.
Unit tests added. Fixes #33.
Refactor methods to the only place they're used
Reorganize package
Merge pull request #29 from agouge/property-fns

Add missing property functions