mutt: Automatically cd into the desktop

This ensures that we're already on the desktop so that if we want to
save attachments, we can save them in the current directory
mutt: Set up alternates, turn off reverse_name

Previously, if I got an email to my @me.com email address (which is
forwarded to my @fonten.io address) and hit reply all, I'd end up
`cc`ing myself on the reply. By setting up alternates, mutt knows which
addresses are 'mine' and so doesn't include them in the `cc` field.

Once I did this, however, replies to emails sent to my @me.com email
address would be sent from that account, which isn't what I wanted. By
disabling `reverse_name`, we force mutt to send emails from the email
address I already specified, as opposed to sending the email from the
account that received the email.
mutt: Add display filter

- Clean up Trello emails with [trelloparse]
- Export temp version of each email. This helps with working on the
  display filter stuff.
- Commented out: recode integration. This _should_ be able to fix HTML
  entities in emails, but results in some wacky fucking bugs that I
  haven't been able to figure out yet. I just want to commit this so
  that I don't lose it.