addcolor - add new colors to the current colormap
addcolor adds new colors given in the c argument to the current colormap. c must be a matrix with 3 columns [R G B] R is red component, G is green component, B is blue component). Each entry in c must be a non negative number less or equal to 1.
The ids of the new colors are returned into new .
If a color defined in c is already present in the current colormap it is not added.
colormap ,