v6.1.0 - Emojis, stability and notifications

Bunch of smaller improvements and bug fixes.

In general, call reliability should now be improved.

Emoji set was switched to the default Google one, along with fixing some parsing issues causing mention chips not to include emojis properly.

Additional things were done in preparation for the v7.0.0 release, including, but not limited to, delete and delete-all which should keep notifications in sync across the devices.

As for the rest - keep looking and you shall see!