examples/shader: Use graphene_euler_t
build: Compile all built sources

The generated enumeration types are missing from the build, and the
generated resources are listed twice.
light: Add properties

And accessors where needed.
ambientlight: Use GthreeLight properties
area: Add properties

And accessors where necessary.
basicmaterial: Add properties

And accessors, where necessary.
buffer: Minor clean up
camera: Add properties
perspectivecamera: Add properties

And accessors, where needed.
texture: Add pixbuf property
pointlight: Add properties

And accessors, where necessary.
Merge pull request #2 from ebassi/properties

Properties