Assorted Guppy updates.

One or two more things added to the compiler generally (langops & similar).
Guppy test_g15.gpp now produces some convincing looking C code that compiles,
but untested, and no semantic checks in the compiler yet (other than trivial
type-checking).
More Guppy updates, including start of TLP handling.

Sort of working, test_g15.gpp compiles successfully to test_g15.c,
and that compiles, links and runs successfully against KRoC 1.6.0+ :).
TLP handling is a little grotty at present (lots of hand-cranked C
code emitted to stitch together things), and little consideration for
stack-space requirements.