KryptEY enhancment

[CertainBot]

@amnesica, first congratulations on this wonderful piece of software! After using it for a while I have a few suggestions for improvements:

1. automatic decrypt option instead of having to press the button each time when an encrypted message is detected in the clipboard.
2. in conversation view sets the viewpoint to the begining of the conversation, should be to the bottom (last message) by default.
3. if there is not a suitable key for decrypting a message as when the conversation is not initialized properly or out of sync, the app minimizes/crashes instead of displaying some message.

Thanks for the great work!