#235 camera rotate and mouse grabbing

[Johan Rehnberg]

Since mouse deltas are sometimes broken in SDL when the mouse is grabbed (sdl_video:wm_grabInput) while the mouse is moving the camera is rotated wrongly sometimes.

How to reproduce:
1. change to Blender camera
2. while moving the mouse fairly fast click middle mouse button -> sometimes you will see the camera gets rotated wrongly

I dont think you need to grab the mouse in wings since you are warping the mouse.
I disabled the do_grab call in wings_io.erl::grab() and things seemed good.

I think this problem happen when mouse motion events are in the event queue when the mouse is grabbed so its strange that peepEvents call in do_grab dont help here.

I am running Wings 1.1.3 on Linux (archlinux).