wumpus-basic

Copperbox revision 1903.

I've fixed the bug with the substError (question-mark-inside-angle-brackets) combinator. It was over keen in replacing the whole failure continuation - it should just replace the failure message of the failure continuation, the failure continuation can have both Fail and Okay.

The AFM v4.1 parser now works for the two examples I've tried it on, though it is far from robust. The main problem is v4.1 has many modes for advance vectors and I don't know what to do about them, for the moment I only want to handle horizontal, left-to-right text.