This performs surgical modification of the IFF chunks rather than
invoking filamat from within matdbg. Low-level direct manipulation
(bypassing optimization passes etc) allows us to diagnose issues with
the shading pipeline.
This CL also adds keystroke bindings to the Monaco editor. You can
press Cmd+S to rebuild the current materials, or use Ctrl+Arrow to
navigate between shader variants and materials.
In a subsequent CL I will add a README that describes how this works in
detail, it will include a list of limitations and a feature wishlist.
