+Implemented orthogonal projection mode for coordinate system. Switching...

+Implemented orthogonal projection mode for coordinate system. Switching to/from this new projection mode can be done via the right-click context menu of the coordinate system. This will not change how the scene in the current viewer is rendered.
+Changed the "Lock view" behaviour. Selecting any of the six fixed views from the coordinate system's right-click context menu's "Viewing Direction" will now lock the rotation, and "Free view" will unlock it. It is still possible to use "Lock rotation" to lock the currently selected rotation.
+Fixed small error in Stereo Viewer

git-svn-id: http://www.openflipper.org/svnrepo/OpenFlipper/branches/Free@10478 383ad7c9-94d9-4d36-a494-682f7c89f535