img.icn: Program to create and edit tiny images

img is a simple editor of Icon image strings and other tiny images.
An image size of 64 x 64 pixels is around the practical maximum.

usage:  img [-cn | -gn] [filename | width [height]]

-c or -g specifies a palette; the default is -c1.

An input file may contain an image string or an image readable by Icon.
If no filename is given, a new image (default size 16 x 16) is created.

img brings up a window within which:

     -- clicking on the color palette sets the color of that mouse button
     -- clicking on the cell grid sets the color of a cell
     -- shift-clicking on the cell grid sets the button color from the cell

     -- pressing "W" writes the image string to standard output
     -- pressing "Q" writes the image string and then exits
     -- pressing "Z" clears all cells to the color of the left mouse button
     -- pressing "O" or "L" toggles palette outlining or labeling
     -- pressing "T" sets the left mouse button to '~' the transparent color
     -- pressing "R" changes pixels matching the right button color
             to be the color of the left button