Don't crash when trying to export linked parts

Fixes issue #1176
Merge branch 'master' of https://github.com/Lirusaito/SingularityViewer
Mats.
Merge branch 'master' of git://github.com/Shyotl/SingularityViewer
Fix fullbright stuff in deferred. Have to re-assess old glow occlusion bugfixes.
Return to our nice ssao.
Add LLGLManager::mIsMobileGF
Merge branch 'master' of git://github.com/Shyotl/SingularityViewer
Merge branch 'master' of https://github.com/singularity-viewer/SingularityViewer