Volume3DPanel - composite image behaviour #11
Description
The Volume3DPanel has some behaviour issues when dealing with multiple/composite images:
- All opacities are set to zero (invisible) by default; set these to one
- When loading an image as a new column, opacities get reset and "Render as composite" is unselected
- New columns with the same name overwrite existing ones; allow name change
- Column names can't easily be changed - implement this
Other minor issues:
- min/max for histogram is large double and significant digits aren't visible; need to format this number
- Text box edits have no effect on the colour map - implement this