Split format string generation into separate file..

    * Also added a generic mechanism 'chance.rkt' for adding
    non-determinism into the system.
Generating precisions correctly.
Split out printf functionality.
Added explicit integer casts.
Added more generated files to 'make-clean' rule.
Now compiling against spencer's vfprintf-fixed.c
Compiling with profiling.
Fixed support for unsigned decimal types.