Add a Pi-approximator.

I loved your blog post, and I wanted to try my hand at this non-alphanumeric stuff too.

I made a little ruby script that approximates pi (= 3.14 ...) using the series expansion of the tangent function. Two things it uses that I don't think you ever used in your post:

1. Getting a Ruby `Float`: I divided the square root of 3 by itself.
2. The `my_lambda.(arg1, arg2)` syntax, which is extra-weird looking for esoteric goodness.

Oh, and if Ruby would support it by default, this guy could use tail-call recursion. Right now it doesn't, and I couldn't figure out how to "unroll" the recursion without using alphanumerics, so high "precision" values cause stack overflows. :frowning: