Move update info URL to new domain

[Montandalar]

The server automatically redirects to the new name, so why not move it on the engine side too?

This seems like a natural checklist item for the renaming. Presumably the old domain was left in for 5.10's release, at an earlier stage of the renaming; but 5.11 does not need to do the same.

How to test

Backdate to 5.9.1, remove common.conf (or the relevant lines update_last_known) from your cache directory, and replace the setting in builtin/settingtypes.conf. It will still find there is an update.

Alternatively, remove the last checked date from common.conf as in method 1, then use wireshark to verify the HTTP request goes through. I just didn't get wireshark working today.

[Montandalar]

Also, the release_info files published still direct the user to download from minetest.net, that should be changed on the server side.

[cx384]

Can we please do this in one go.
At least for the whole www.minetest.net. subdomain.
So just execute this:

git ls-files | grep -v "\.ico$" | xargs sed -i "s/www\.minetest\.net/www\.luanti\.org/g"

(I'm not sure about the "MS Windows icon resource" file, so it's excluded, but everything else should be fine as far as I can tell.)