No-DNS Chatmail relay

With this branch, you don't need DNS at all, just a VPS with an IPv4 address, let's take 77.42.80.106 as an example. First, choose a random domain name (it doesn't need working DNS) and create a chatmail.ini config file:

cmdeploy init [77.42.80.106]

Then, in cmdeploy/src/cmdeploy/postfix/transport, remove the line corresponding to your relay, and add other for relays you know. Now you can deploy the relay to your IP address:

cmdeploy run --skip-dns-check --ssh-host 77.42.80.106

Finally, you can login with a dclogin:// code like this, with the correct "domain name" and IP address:

dclogin:s0mer4nd0@[77.42.80.106]?p=w7i8da7h8uads92ycc2rufyl&v=1&ih=77.42.80.106&sh=77.42.80.106&sp=443&ip=443&ic=3&sc=3