Stable ABI

Across all architectures, some offset are referred to by off-
sets that don't change (well, not without some binary manipu-
lation). Here's the complete list of these references:

04 BOOT addr         06 (uflw) addr      08 LATEST
2b (s) wordref       33 2>R wordref      42 EXIT wordref
53 (br) wordref      67 (?br) wordref    80 (loop) wordref
bf (n) wordref

BOOT and (uflw) exist because they are referred to before those
words are defined (in core words). LATEST is a critical part
of the initialization sequence.

                                                        (cont.)