Note a problem in need of fixing about the CSV loader.
Make Scheduler robust against exceptions in scheduled calls.
Remove delays from spectrum view updates on scroll.

* Introduce a notion of invoking a scheduled callback immediately (in
  place of any later scheduled call) and use it for SpectrumView
  recalculations.

* Introduce a wrapper for event listeners which causes the scheduler to
  run after the listener finishes.

This reduces jump-glitches when zooming while also moving the cursor
over the spectrum view.