GlobeControls trackball drift: before / after

Demo for 3DTilesRendererJS PR #1723 (fixes #808). Both pages are the stock mapTiles example (OpenStreetMap tiles on a globe).

Before (master)

Open the example built from master

After (PR #1723)

Open the example built from the fix branch

How to reproduce the drift

Press and hold the left mouse button on the globe, drag the cursor in two or three full circles, then bring the cursor back exactly where you started and release.

Before: the globe ends up visibly rolled. After: it returns to its starting orientation.