genfoam.c: Don't generate (Seq (Cast (....)); it should always be
equivalent to .....
Make note in gf_prog.c that outer casts are not allowed.
tform.c: Add Category to things that can contain conditions.
libax0: Add a few tactical 'import from Boolean' where needed.  This avoids
an assertion failure.  Really ought to dig out the cause of Boolean not
being imported automagically, but not high priority.