Added ShaderDemo Example.

Signed-off-by: CoffeeParser <denis.dik@hs-furtwangen.de>
Merge branch 'feat_text_gui' of https://github.com/FUSEEProjectTeam/Fusee into feat_text_gui
InitialPush

Signed-off-by: CoffeeParser <denis.dik@hs-furtwangen.de>