Hugo Lefeuvre authored May 14, 2018 and Sébastien Blin committed May 30, 2018

Currently the navbar is implemented in native GTK, and has a pretty
bad integration with the chatview. In this patch we implement a
modern navbar *in* the chatview and remove the old GTK bar.

*Changes summary*

chatview, HTML/JS/CSS side:
- Remove useless function setSendIcon from the chatview
- Simplify setTemporary in the chatview
- Use only one single showInvitation function instead of two
  showInvitation and hideInvitation functions.
- Remove pointless/copy&pasted comments

chatview, GTK side:
- Simplify chatview update methods: instead of providing several
separate functions to update the invitation/banned status of the chat
view, only provide one (update_chatview_frame). This should have a
good impact on the performances and simplify webkit crash handling.

Change-Id: I6959240efd357fedb07d3c60d551efc8fca84812
Reviewed-by: Sebastien Blin <sebastien.blin@savoirfairelinux.com>