Fixed SceneGraph multipass and single pass rendering.

Previously the standard enter and leave functions had been active for picking too,
resulting in picking failiures when e.g. Blending was active.

git-svn-id: http://www.openflipper.org/svnrepo/OpenFlipper/branches/Free@8857 383ad7c9-94d9-4d36-a494-682f7c89f535