In-app messages

Implemented notifications system - now each user has their own inbox and can browse it at any moment in the app. The primary use case for this right now will be to add feedback to your reports. You will be seeing when your bug report was closed, you'll see my comment, etc.

Bugfixes/Improvements

• [BehaviorTree] Fixed the problem with middle-click selection
• [SendSequence] Restore Mouse Position was not saved correctly