TrackMate_: performance tweak for the track colorer.

Since for this class we generate a single color for a whole track, we
might as well using caching to avoid re-fetching the color at each call.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
TrackMate_: performance tweaks for the tracks display.

The track overlay in the HyperStackDisplayer does not care whether the
track IDs it has to paint are returned sorted or not. But sorting takes
a good amount of time. So this commit introduces a method that returns
trackIDs unsorted.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
MaMuT_: performance improvement of the track overlay.

The track drawing is the slowest part of MaMuT, and is punitive when a
large number of large tracks are to be drawn. This commit improves the
drawing performance by using the tweaks introduced recently in
TrackMate.

Unfortunately, the track rendering is still too slow. However now, the
slow part is cornered to be the call to native drawing method
sun.java2d.SunGraphics2D.drawLine(int, int, int, int)

The Yourkit profiler (v12.0.2) reports that this method takes 99% of the
time of
net.imglib2.ui.InteractiveDisplayCanvasComponent.paintComponent(Graphics).
Event fine profiling concord.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>