Color by speed or age on GPX traces

[BalooUriza]

I was wondering if we could get the stylesheets changed so traces without
timestamps could be changed to grey instead of purple by default? With
them being purple, it's difficult to tell if the data point is going
*really* fast or is the freshest available, or just time/speed unknown.

[simon04]

This seems easy. Changing the else for case velocity in source:trunk/src/org/openstreetmap/josm/gui/layer/GpxLayer.java​ to neutralColor should do the trick.

Any counter arguments?

[simon04]

In 6775/josm:

fix #9600 - GpxLayer: use neutral track color if speed is zero (velocity mode) or time extent is very short (time mode)