make sure that the primary camera is always active, even with > 1 camera

[bls337]

It looks like the old code to make sure the primary camera is active only worked for systems that have 1 camera.

On systems with more than 1 camera, the default state for all cameras would be false.

I also added a try/catch to deal with some NPEs when the camera is "Undefined".

Old code:
// Note: there is no ui control to change the active state of the
// camera when there is only 1 camera, so make sure it's active.
cameras.add(new CameraData(name, cameraNames.length == 1));

New code:
// the first camera is always the default primary camera, so make sure it's active
cameras.add(new CameraData(cameraNames[i], i == 0));

[bls337]

Fixes #377