Improve bottlenecks, scan timings

This version fixes several issues related to scan timing and screen updates. Scans with lots of endpoints (e.g. multi-segment lines, circles etc...) now have all the moves sent to the stage controller to queue up so they execute faster without pauses between endpoints. Each major component (stages, laser, microscope) now has its own command queue so events for each component can be processed in parallel. Stage position updates (which also update the graphics on the screen) no longer get blocked in the event queue behind all other events so they happen faster.