[Coco] 6309 port of NitrOS-9 Level 1

[Robert Gault]

Tormod,

One thing I consider critical. Don't post any Level1 Coco3 patches without 
testing the results. There is at the moment fair degree of non-reproducibility 
for 6309 results and it is vital to check that Level1 6809 packages still work.

Some of these changes could be carried over to Level2 making double checking of 
results that much more important. I've been known to make mistakes and have 
oversights in reporting code. :)

Robert