Sat Jul 18 11:57:01 CEST 2009

getting rid of the return value

Currently the combination longjmp and return for error signalling is
too complicated.  It's probably best to get rid of the return value
all together and use guarded execution in setjmp wherever it's
necessary to call primitives from C.

Basic idea: if a primitive has an error, it returns to the interpreter
loop and abandons its C stack.

Ok, this looks like it's tedious but quite straightforward.  One thing
though: write (serialize) should be able to fail.

ok i got it to build..
now let's spend some time in the debugger..