Video and voice calls

Video and audio calling

Other changes:
094ae50 Update ChatListVC when app becomes active again.
ddd496b Added link to translations instructions
f984670 Fix crash with missing segue
e0fd7e9 Visual tweaks
04426d6 Fix font styling in quotes
94ade45 Fix selection of message previews, remove redundant code
935fc0b Remove Pods/* from git
6f43cdc Provide pod installation instructions
099c04c Do not log out of app on network errors.
81b5e77 Retain account across DB updates to avoid logout