Added tutorial examples
Added quad tutorial examples
Merge branch 'gl-gloo-merge2' of github.com:vispy/vispy into gl-gloo-merge2

* 'gl-gloo-merge2' of github.com:vispy/vispy:
  Dont use `except:`!
Flakification
Fixed galaxy demo
Fixed donut demo
Flakification
Fix texture coordinates
Added post-processing example and moved app into tutorial
Rewrote the GL fireworks version
Delete rawgl directory that now lives in tutorial/gl
Remove texturing.py example becaus is already in tutorial/gloo
Remove spinning-cube.py example because it is already in tutorial/gloo
Added grid techniques
Added rain demo
Flakification
Added Gray-Scott reaction diffusion demo
Separated explcitly render/compute viewports
Rewrote game of life in order to show GPU speed
Fixed header