Allow dragging of coloured pegs from previous guesses. Also

Allow dragging of coloured pegs from previous guesses. Also
reorganise the colours so there are fewer of those terribly
computery cyan and magenta shades, and more good old-fashioned
colours with simple names like orange and purple. Finally, change
the `right place' marking peg colour from red to black, in line with
at least _my_ old Mastermind set (I faintly suspect red marker pegs
of being an Americanism) and also so that the marker pegs and the
coloured pegs have no colours in common.

[originally from svn r5995]