Conversation Page rewrite

This should make spacebar somewhat usable and not too ugly as an SMS client.

• Removal of :smile: emoji syntax in favor of unicode emojis. This allows to display emoijis in the conversation messages, and speeds up loading a lot. The new primary way of sending emojis is using the emoji picker.
• Instead of loading the MainPage only when telepathy is ready, display a spinner while telepathy is loading
• Fix display of user name / user id on log page

Possible reviewers: @schmeisser (because you have a working test setup as well) @bshah (because he can test it on his pinephone)