Merge pull request #134 from Edilbert/master

Make the colon ':' optional in B-X block commands
Fix B-A: for already allocated blocks

Returning -1 forces setting the status to SYNTAX ERROR, so
return 65 (NO_BLOCK) preserving the NO BLOCK message with T&S set.
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