A few minor ui changes written on TerraBus rides over the Ross Ice Shelf....

1) change the colour of the change file and change range icon data line
to provide slighly better visual clues

2) Make changefiledialog and changnpts dialogs into Apply/OK/Cancel
dialogs rather than Apply/close dialogs.

3) Double clicking on a curve in a 2d plot now opens the curve dialog, not the curve's provider... (the previous behavior was inconsistent and confusing, even for me, who defined it in the first place...)