Initial handshake

It doesn't hurt, but I see that Amy answers to `xboard` what it should answer to `protover N`, according to [CECP protocol](http://hgm.nubati.net/CECP.html).

```
White(1): xboard

feature myname="Amy 0.9.6"
feature san=1
feature name=1
feature done=1
protover 2
quit
```