Update ply_io.cpp

Reading a binary PLY file with faces and "vertex_indices" property crashes, if only a PointCloud is provided. Since the polygons_ member is set to 0 and untouched otherwise.

Worked in PCL 1.6, doesn't work right now with 1.7.1.

The ply2pcd sample program provided with PCL crashes as well.
Moved computeRoots2 implementation into hpp
Moved computeRoots implementation into hpp
Moved eigen22 implementation into hpp
Moved computeCorrespondingEigenVector implementation into hpp
Moved eigen33 implementation into hpp
Moved invert2x2 implementation into hpp
Moved invert3x3SymMatrix implementation into hpp
Moved invert3x3Matrix implementation into hpp
Moved determinant3x3Matrix implementation into hpp + missing documentation written
Templated getEulerAngles
Templated getTranslationAndEulerAngles
Inlined one of the getTransformation function
Identation corrections in the test unit
Added inlined transformPoint
Added inlined transformVector
Added transformLine + test unit
Added transformPlane + test unit
Added checkCoordinateSystem + test unit
Added transformBetween2CoordinateSystems + test unit