Added new mMeshManipulator method scaleTCoords to scale texture coords of a mesh. Added two new access methods to texture coords of vertices of a meshbuffer. This allowed to replace the template for planar mapping as well.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@1479 dfc29bdd-3216-0410-991c-e03cc46cb475