Extrude and move arm at the same time, in time

Depends on #11 (closed)

• Send trajectory and monitor feedback
• Control extruder and motion simulataneously
• Extrude at fixed rate while moving
• Fix any timing issues (extrusion must start exactly/before arm movement)
• Execute multiple contours with extrusion
• Fix any extract/retract issues (these will need to be accounted for by the planner)
• Change to better extrusion method if not good enough
• Check extrusion over multiple layers
• Multiple layer print on multiple parts of the print bed (with both arms individually)

changed milestone to %Single Arm Printing

added enhancement label

changed time estimate to 3d

changed the description

changed time estimate to 1w

changed the description

added Doing label

changed the description

mentioned in commit 2e3651c9

marked the checklist item Send trajectory and monitor feedback as completed

mentioned in commit dcc5df41

mentioned in commit 7d4e8c57

mentioned in commit 272fd987

marked the checklist item Control extruder and motion simulataneously as completed

mentioned in commit 2e0e5e53

marked the checklist item Extrude at fixed rate while moving as completed

mentioned in commit e73014d2

mentioned in commit twins-planner@b50d1971

mentioned in commit 472cbc7b

marked the checklist item Fix any timing issues (extrusion must start exactly/before arm movement) as completed