Bugfix: Fix cursor display precision
Bugfix: Fix cursor display precision

Transform the cursor relative to the camera position before sending to
OpenGL so that we don't loose precision by converting to float32.
(partial fix for #33)

rotorliu/displaz,JoshChristie/displaz,JoshChristie/displaz,rotorliu/displaz,rotorliu/displaz,JoshChristie/displaz,JoshChristie/displaz,rotorliu/displaz,JoshChristie/displaz