GPU class: @gpu.object class decorator allows its methods decorated with @gpu.method to be translated with the GLSL backend.
In the @gpu.main function an list of MyObject can be iterated over and methods called.
gpu class: fixed method subroutines.
allow integer types, wrap number with `int16(n)`
updated GPU doc
pack external javascript objects for upload to GPU
directly translate THREE.Vector3 to GLSL vec3.
gpu.object(class, name) function, updated GPU readme.