EarClipping algorithm improved + typing error in Clipper3D

Due to a commit-mistake, I mixed two different pull request in this one:

- In clipper3D.h there are two spelling mistakes using Clipper3d instead of Clipper3D as template parameters. This does not compile with MSVC2010.

- EarClipping algorithm failed for polygons, where are vertices have the same x or y component: http://www.pcl-users.org/earClipper-isEar-for-flat-triangles-in-XY-plane-td4028199.html. In the new implementation, the earClipping is calculated in 3D instead of projecting all points to the XY-plane.

Sorry about mixing about two different things, but the first one is really tiny.