In celebration of my second commit on weboob

Since no one seems to use it.
I fixed the biggest issues so it is now usable again!

While this changes constants names, I think it is important as "accused" is
complely wrong. E-mails use the term "Read-receipts" so I chose
to go with RECEIVED.

Move to .se, remove https for downloads, use the correct link for
downloads.
And some cosmetic enhancements

Probably the result of a bad merge