[FIX] Apply the correct rules for PGP inline processed messages [#203]
Merge branch 'dev' of github.com:GPGTools/GPGMail into dev
Merge branch 'dev' of github.com:GPGTools/GPGMail into dev
[FIX] Remove nasty sender automatically in BCC bug. [#509 state:fixed]
[FIX] Scheduling messages for having rules applied should no longer crash. [#605 state:fixed]

- The check whether messages have already been scheduled is performed
  on a serial queue, so it should be assured, that each message is really
  only scheduled once.
- Applying the rules is performed on a background thread.