Separate timeline for 3-D World View

[Stephen Gatesy]

Being able to play the 3-D World View much faster than the entire timeline video controller would be helpful. It's tough to identify points if they aren't moving quickly. Being able to disable the video rendering would be fine if that speeds things up.

[Benjamin Knorlein]

fixes #91 : Added an extra timeline in the 3D worldview which can be enabled and decouples the 3D view from the mainwindows controls

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