Fix cfor inlining bug.

This ended up being a bit subtle. Basically, the transform() method
doesn't correctly handle the following kinds of trees:

TypeTree().setOriginal($tree)

Basically, in this case transform() method doesn't recursive into the
$tree, but the $tree is actually where the important code is. We fix
this by matching TypeTree explicitly and calling transform($tree) when
$tree is not null.
add thyme dependency
Introduce expm1 and log1p to Trig[A].

These methods are needed to make generic programming safe for
floating-point values.

Right now, Complex[A]#log1p and Complex[A]#expm1 use naive
implementations for these. Arguably, if a complex number is real
(i.e. has no imaginary part) we should instead use Trig[A]#log1p
and Trig[A]#expm1.