Change FILE NOT FOUND CODE from 39 to 62

CBM DOS usually reports 62 for files not found.
The only exception seems to be 39 if a utility file aka
command file was not found.

For further information, please have a look at
http://commodore64.se/wiki/index.php/1541_tricks
Fix compilation with #define DEBUG 0 in debug.h
Some cleanup. Start work on assign
Merge branch 'master' of github.com:fachat/XD2031 into filetypes