add read float buffer example

Added missing dependencies for sae3d examples.

http://zz85.github.io/mrdoobapproves/

Removed shading property for MeshNormalMaterial

the example reads the background texture point under the mouse and
displays the value on the window.

@nraynaud do you mind double checking that I didn't break anything?

Make readRenderTargetPixels() compatible with float extensions

Updated to latest Raycaster.params

Minor cleanup in postprocessing glitch example

Minor cleanup in extrude splines example

Fixed loader md2 example

Fix for retina displays