Native v7.0.0

This release improves message syncing in the app while running and while the app is backgrounded.

• Adds a new background task which fetches messages in channels and DMs while the app is backgrounded
• Adds support for the new /changes and /range endpoints for efficient message delta retrieval
• Adds support for sequence numbers in channels and DMs such that messages are displayed in the order they are sent for everyone in the group or DM
• Fixes an issue where the "Connecting…" status would hang indeterminately
• Fixes an issue where viewing a group preview would cause performance issues on the server
• Fixes an issue where historical incomplete image uploads would cause degraded performance
• Fixes an issue where image uploads in avatar and group info fields would fail silently
• Fixes an issue where pending messages sent in a thread would briefly reappear in the main channel until sent, or stick in the main channel if failed
• Fixes an issue where lots of roles in the channel permission fields would not wrap to the next line