Sets the rendering material override of the entity.
To set a Lua material created with CreateMaterial, just prepend a "!" to the material name.
If you wish to override a single material on the model, use Entity:SetSubMaterial instead.
Please note that to apply materials to models, that material must have VertexLitGeneric shader. For that reason you cannot apply map textures onto models, map textures use a different material shader - LightmappedGeneric.
The server's value takes priority on the client.