Added a check against a null fb
Merge pull request #201 from TheNeikos/fix-sf_commit_blit_null_check

Added a check against a null fb
Add method for getting a surace from a resource
Add initial version of shell surface datatype
Add wayland shell surface interface implementation stubs
Add constructor
Add files for wayland shell interface implementation
Add wayland shell interface stubs
Add initialisation of wayland shell
Implement method for getting a shell surface
Initialize wayland shell from ws_compositor_init()