add flag to disable camera

[agurvich]

lock users to a tween params path but let them use filters, etc.

[agurvich]

https://discourse.threejs.org/t/enable-disable-controls/3055/3

can disable trackball controls but the call to controls.update in renderLoop is necessary to re-point camera in trackball controls. might need to update how tweening is done to re-point camera because tweening in fly controls is the same as tweening with the controls.update call commented out

[agurvich]

should not happen until we've cleared: https://github.com/ageller/Firefly/issues/91 and improved tween support. As it is now tweening is still pretty experimental

[agurvich]

after learning more about the controls, seems like we should be able to disable or remap the mouse buttons events associated with activating pan, rotate, and zoom (https://threejs.org/docs/#examples/en/controls/TrackballControls.mouseButtons).