Matrix app improvements

[CRImier]

Features

• [ ] Support invites into rooms; accepting/blocking them
• [x] Leave messages should be visible (optionally, hideable)
• Encryption
  • Probably needs the SDK to be more mature
  • [ ] Device key verification should be possible from the UI
• [x] Highlight notifications (when your nickname is mentioned in the message text)
• [x] Showing members of the group (once RIGHT in the room menu is free, it could be available on RIGHT press)

Usability

• [ ] Join messages should be hideable - globally and per channel
• [ ] Leaves and joins should be grouped into messages - if we get one message, three leaves/joins and then one message, that should show as three entries in the UI
• [ ] When an encrypted room is visited, there should be a warning shown if encryption is not enabled (there's a nice flag in matrix_client library that allows to check for that)
• [x] Writing messages while you're in the chat should be possible
• [ ] There's a "interpret a username as your own" function (to show messages you sent from IRC/other account as your own), but it's not exposed in the UI yet - needs to be, in some way
• [ ] When "Load more" is navigated to, the UI shouldn't refresh in a way that makes the first_displayed_entry in the view shift, making the currently selected entry jump from top to bottom of the screen - it's distracting (should be easy with the #109-provided mechanism )
• [ ] Saving messages in a database of some sort for offline viewing
• [x] If a token is saved and available in the config file, the app should login in the background, as soon as the app is loaded (using something like BackgroundRunner)

Reliability

• [ ] It's yet unknown how the SDK handles losing the network connection - which is inevitable with a portable device like ZP
• [ ] When network connection is lost, sending messages throws an exception
• [ ] When network is unavailable, app crashes when activating it
• [ ] In case message sending fails, we need to store the message somewhere and resend it as soon as connection is re-established
• [ ] Does message loading on "Load more" crash if network connection is lost?
• [ ] What if Matrix servers crash? It's happened recently (they were returning 403 on login with a token)
• [ ] I've encountered a problem where, say, event['content'] would be an empty dict. I've started replacing dict[key] constructs with dict.get(key, reasonable_failsafe_value) ( 50038d49755 ), but there's certainly more places to do that (and reasonable defaults have to be found for each of those places).

Other

• Once we have notifications, they will have to be added
• When new rooms are added, when are they enumerated and added to the room list?

@derivmug add your own points in a separate comment =)

[CRImier]

Observed the app - imitated network connection loss with wpa_cli app's "Reconnect" function, messages arrived after connection was restored. Need to test further.

[CRImier]

Tested a little further - removing network connection for a minute (route del default) does not seem to raise any exceptions; however, sending a message while offline does throw an exception.