[Coco] Fragmented bootfile support in NitrOS-9

[Boisy G. Pitre]

For those of you who have cursed OS-9 for its inability to handle  
fragmented bootfiles, I have some good news.  Today, I successfully  
added to boot_1773 the ability to read fragmented bootfiles.  There  
is additional testing that needs to happen, as well as several more  
booters that need to be adapted, so this feature will be part of the  
03.02.06 release of NitrOS-9.

This new feature necessitated a change to os9gen.  There is a new  
option, tentatively labeled -b, which acts like the similar bootgen  
command from OS-9/68K.  If this option is specified, then os9gen will  
create the OS9Boot file on the target device in such a way that it  
can be fragmented.  Without the -b option, os9gen will behave as  
normal (that is, not allowing fragmented bootfiles).

Boisy