Added Samples and Disk Images

* Added some BMP files to show the different supported formats. All
copyrights belong to theis respective owners.
* Added Palettes to convert images using GIMP. The NTSC version is
based on the "exact" RGB values calculation from
http://mrob.com/pub/xapple2/colors.html
* Added ProDOS and DOS3.3 disk images with some of the samples and the
assembled binaries.