Add GUI with OpenGL integration, doesn't work on OSX but may work in Windows and Linux. Needs to be tested.

Signed-off-by: Adrien <berthet.a@gmail.com>
Merge branch 'master' of https://github.com/karimnaaji/particle-system into gui
Seems like we're getting closer to a correct window...

Signed-off-by: Adrien <berthet.a@gmail.com>
GUI finally working 

Signed-off-by: Adrien <berthet.a@gmail.com>
Much beautiful 

Signed-off-by: Adrien <berthet.a@gmail.com>
merge gui in master