Moved the virtual servers

[mtbc]

Finally, I got around to the virtual server migration, rather last-minute. At least, I got the more critical parts, DNS and e-mail, working sufficiently the day before the deadline. I will get around to the other parts over time. It was fun to get back into that kind of work, and interesting to be reminded of how I had set things up previously. Thank you to those who offered suggestions: in the end, Mythic Beasts looked very much to be the right kind of provider and, so far, I am happy with the move to them.

Apart from other services, even my initial ones still need a bit of work: get my zones offered by the provider's DNS too, review the SSL certificates for SMTP/IMAP, sort out DMARC, etc. Still, things are already working well enough that I'll continue at my convenience.