Instructions / Replay module

In order to allowing viewing of surgical instruction in the OR.

Basic idea:
After each action, the planner saves some descriptive action name ("Bend Model Blah") and the current state of the model hierarchy, to a txt file:
Bending Model Blah, BendingModelBlah.mrb (this mrml scene should contain just the hierarchy)

We want to use the .mrb format so that we can avoid having a folder with just 100 models in it. .mrb will keep it better organized

Edit: using screenshots instead, no replay module at this time

Functionality needed in Planner:

- [x] Detecting end of transform actions (cut/bend already have well defined end states)
- [x] Saving screenshots of 3d view

- [x] Menu to control screenshot grab

- [x] Creating instructions list