Improved `each` testing some
Changed `src` to not use JSON serialization

Serializing to JSON means we can't serialize functions, which
is a bit of a bummer. Forgot about that.
Added `variadic` for producing variadic functions

Just makes it easier to deal with variadic functions, by
always making the last param be an array. Not sure about the
way this is implemented. It compiles a function on the fly
using `eval`. Performance tests suggests this is no big deal,
and there should be no security issues since there's no
custom code being compiled.

But it smells. I don't like smelly things. Unless it's
cheese, then it might be ok.
Added `trampoline` function
Changed `thunk` to use `variadic`

Well that was nice.