bmp code now raises an exception for a unknown BMP format.
bmp code now raises an exception for a unknown BMP format.

Before it would have done a writeln() which would go unnoticed under
Linux, and cause an AV under Windows GUI apps.

wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI