Release 1.5 rc3

• Move shown image area by dragging with left button and alt/cntrl pressed
• Upper Fork and Key Area derived list for actual area
• Back and Forth menu item
• merging rasters to solve problems with superfractalthing maths.
• special area names (ref) for merge support
• adjustment tab for image control
• exponential mapper (experimental)
• saving modified raster
• next/prev for colormap lists
• color chooser scroll color bar
• fix: optimal mapper with colormap substitution and resize
• fix: color chooser labels
• fix: number field resize on mandel area views (DPI schange)
• fix: color sample on color chooser (DPI change)