Linux fixes..

Got this working on linux :)

Should make sure I haven't broken things on windows before merging.


Changes:   made build.sh to build
Removed refs to:  wglew (includes glew anyway so should be fine)
Import Image from PIL - (so this works on Pillow)

Had to change a bunch of things to explicitly to floats so that the shaders don't complain*  - this bit I'm the least sure about - does it change the output ??


Running in linux:
```
$ cd lib
$ sh build.sh
$ cd ..
$ python main.py

^ note on laptops (like mine) with nvidia + intel, need to run under optirun or equivilent:

$ optirun python main.py
```

Output:  http://imgur.com/9k5mUse