Small updates to Guppy.
Small fixes to Guppy 'while' (incomplete).
Assorted updates for Guppy, not complete as yet.
More assorted Guppy updates.

Allocator is working a bit more sensibly now;  probably not reserving
enough C stack space in the generated code yet, but test_g29 deadlocks
rather than segfaults.  Should allocate workspaces statically where
possible (dependant on scoping in source).