Fixed trust icons

[opatut]

• two more trust icons (none, marginal), now showing up like this
  • none: 3 gray dots; if no key is found (recipient list only)
  • invalid: 1 red dot; if key is invalid (expired)
  • untrusted: 2 yellow dots
  • marginal: 2 green dots (important for sign-on-first-contact)
  • trusted: 3 green dots (if manually signed)
• fixes compose window recipient list icons

[opatut]

We still need to fix the secret key list (#24), before merging this.