Sliders don't work with xml3d camera.js

[Arsakes]

The fact that camera.js (tool script that goes with git version of xml) attaches mousemove and mouseclick handlers to the document make it impossible to use sliders (<input type="range">).

[csvurt]

Yeah it looks like a check was lost in a merge conflict, these events are being stopped when they shouldn't be. I'll take a look today and see if I can improve the event logic a bit, I think this is the second time we've had a problem with these things...