To make a new logo:

  1)  Create the logo image by some means (f.e. with gimp).
      Size should be no larger than 512x512
  2)  Export the image to FITS
  3)  Convert the FITS file to the header:

        $ python3 mkhdr.py
	$ mv logo.h ..

  5)  Recompile the XImtool sources.
