get mouse-drag scrolling working in regionbrowser2, with bugfixes to quant track updating
factor animation out of projection system into JBrowse/Util
fixup! factor
make mouse-drag scrolling have momentum
reduce max speed of momentum scrolling
add some smoothing to momentum scrolling
more mouse momentum tweaks
bugfixes to block rendering
don't update the projection when mouse dragging if the mouse has not actually moved:
fix propagation of config callbacks into workers
improve synchronization of quant track updategraphs
fire a last scroll move event when mouse momentum is canceled
comment out loading timeout code for now
bugfix to byte-range caching
optimize deserialization code a bit
switch remote dom node code to an eval-based algorithm, might be faster
remove old locationscale track
convert quant tracks back to rendering in the main thread.  actually faster.
speed up locationscale and gridline updates
more perf