Minor fixes to README.md
Starter .gitignore
Second night's commit.

We're a bit closer to something sane, now. We can wrap, but not unwrap,
packets.

Asymmetric encryption is *big*. encrypted text with a 4096-bit RSA
public key is 512 bytes. We can't fragment yet. Fortunately, this
isn't an infinite regress once we *can* fragment.

Performance is still a big question mark, of course.

There may still be endianness issues hanging around.

The eid<->rloc map is almost certainly far, far too slow to be of
any use in the real world.