#1052 confusing hidden autocrypt entries in pgprules.xml

[kolAflash]

Proposal: Add a checkbox to unhide "automatic rules" (e.g. autocrypt:// rules) in the Per-Receipient rules UI.

I just spend nearly an hour, figuring out why Enimail chooses to encrypt when writing to a mail address for which there's no public key.

I quickly discovered, that a mail I received from that mail address had an autocrypt header. This header announced a key which does not list the address that mail came from.
mail from: arthur.dent@mailbox.org
key in autocrypt header: arthur.dent@some-university.edu
So Arthur made the interesting choice to receive mails to @mailbox.org, encrypted with a key for @some-university.edu
Interesting choice, but not my business...

The strange thing was, that I couldn't figure why Enigmail follows this rule every time I write a new mail (not replying) to arthur.dent@mailbox.org. I checked the Per-Receipient rules and all Enigmail settings. Even the about:config / prefs.js configurations. But there was nothing.

Finally I figured out, that Enigmail stores it's rules in pgprules.xml. And that those rules prefixing the mail address with autocrypt:// won't be listed in the Per-Receipient rules UI.

[Patrick Brunschwig]

Implemented a checkbox that displays Autocrypt rules. These rules cannot be edited, only deletion is possible. The checkbox is only visible in Advance mode.