Improve support for material constant types

[Jhonnyg]

Currently Defold only supports setting and getting material constants via go.set / go.get - vec4 and mat4. We can now support a wider range of types with this system:

Numbers and vector types: float, vec2, vec3, vec4
Matrix types: mat2, mat3, mat4

Example:

// my_shader.fp
uniform vec2 mouse_pos;
uniform mat3 camera_rotation;

go.set("#model", "mouse_pos", vmath.vector3(self.mouse_x, self.mouse_y, 0))
go.set("#model" "camera_rotation", go.get_rotation(...))