Validate power levels event changes. Change error messages to be more helpful. Fix bug where we checked the wrong power levels

BF: tab completion did not work with commands. $scope.input contained only the typed chars not the result of the completion.
Needed to fire an event so that ng update the input model

This reverts commit f286a4fc.

Show the message sending flow state in the messages list:
  - While sending, the message appears semi transparent in the chat.
  - If successfully sent, it appears as before, ie normal
  - In case of failure, it appears in red with an Unsent text.

switch IRC-style command parser to use regexps rather than split(" ") so that it doesn't choke on consecutive whitespaces
yield better errors for invalid commands
don't pass invalid commands through as messages
support kick reasons

BF: presence PUT requests stopped to work with old "state" param yesterday evening :( -https://github.com/matrix-org/synapse/commit/cda31fb7553ba3d880de09a464ae3b62ea6632fc?diff=unified

BF: presence PUT requests stopped to work with old "state" param yesterday evening :( -https://github.com/matrix-org/synapse/commit/cda31fb7553ba3d880de09a464ae3b62ea6632fc?diff=unified