Merge changes I1d3569da,Ic6d95ccc,I999c43fd,Ie68b9124,I91e6a21f, ...

* changes:
  rusty-gd: more controller
  rusty-gd: controller supported commands & le buffer sizes
  rusty-gd: A bit more controller
  rusty-gd: add intos for builders, so we can skip the formal build call
  rusty-gd: start controller module
  rusty-gd: simplify queued & pending commands
  rusty-gd: make scalar getters return by copy rather than ref
  rusty-gd: drastically simplify command sending
  rusty-gd: improve ergonomics of sending commands a bit