The new class WFPalette encapsulates waterfall palettes including
exporting and importing to disk files and interpolation for use in the
waterfall plotter.
A special entry in the palette list "User Defined" is now available
along with a button to invoke a colour palette designer. The user
defined palette definition is persistent across runs as it is saved in
the application settings file.
Palettes can now have any number of colours up to 256.
The export function may be used to save user designed palettes; to be
added to the built in resource palettes that are shipped with the
application.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@3964 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
