better and shorter pulse

after the feedback from @cmeerw I took an additional look at the CoSeMe library and I found the pong feature to keep the stream alive. I changed the pulse to send a pong. In addition I moved the pulse from the account into the CoSeMe connector. I think this is better now.
avoid multiple pulse intervals
fix for #534

This dispateches a event when the app is ready. So we can now wait until we register the mesage handler.
Merge pull request #585 from TitanNano/dev

fix for #534
Merge pull request #586 from TitanNano/pulse

 better and shorter pulse
fix for #492
Merge pull request #587 from TitanNano/dev

fixes #492
fixes #563

This implements an message sent indicator:
- yellow message -> trying to send the message
- red (default color) -> message successfully sent
- gray with red border -> failed to send the message

Note: If the message gets successfully sent but Loqui disconnects right after that and does not recive the sent ACK from WhatsApp, then the message still gets marked as failed. Eventually the message changes to send when Loqui reconnects and received the ACK.
Merge pull request #588 from TitanNano/improved-send-status

fixes #563
chat settings fix and improvements
group chats can be hidden too, sorry
Merge pull request #589 from TitanNano/dev

chat settings fix and improvements