The "X:" word

Because the ";" word goes back only one level in RSP and
this limits our ability to separate X: in sub words and this
means a rather cramped B265. This means no inline comments,
hence this block here.

0x0e is compiledWord. first _find is on xdict. If found, we
compile it with offsets. We abort on IMMED? because we're
never supposed to encounter an immediate at this point.

If not found, we try the same word on system dict (RAM+02).
If found and is immediate, execute. If founf and not immediate,
error. If not found, try number.
