Celeritas #002

I added a state struct to the RenderGraph module that holds the render graph and a hashtable for looking up texture_handles and then changed the callsites and places which were taking the graph directly to take that.

(* Inside the RenderGraph Module *)
type state = {
  textures: (string, Core.texture_handle) Hashtbl.t;
}

type t = {
  state: state;
  graph: graph (* remember graph is our generic graph that we
                  specialised with nodes = Resource / Pass
                  and edges = Read / Write / ReadWrite types *)
}

And so our initialise pass over the render graph can now store the texture_handle returned from C.