Move the scene updates to the GLWidget class

Change-Id: I1a7c6344b3fea0e2ae02c70f7adf6fbb2eeadd3c
Moved signal-slot connections to the GLWidget

Removed the udpateScenePlugins entirely, this can all be taken care of
by the GLWidget now.

Change-Id: I75910438580c460caeec95565d6d6544c2c9fa69
Merge topic 'glwidget-scene' into master

0699fa87 Moved signal-slot connections to the GLWidget
838e9d9d Move the scene updates to the GLWidget class