updates #1111

* Checkmark and edit modal button are now on the right
* Instead of showing checkmarks for MUC messages,
  we now show them as light grey before MUC reflection
* Simplify message markup by requiring less `if` statements

Also, set the resource in `setUserJID`

- New plugin `converse-smacks`
- New config option `enable_smacks`
- Rename session cache id from `converse.bosh-session` to `converse.session`
- Refactor logout and login as consistently used api methods
- Refactor session cache to store per JID

Fixes #316

So that we can specify defaults

When a synchronous event is fired, Converse will wait for all
promises returned by the event's handlers to finish before continuing.

if the page is reloaded while the nickname form is shown

We now use CSS to make sure that the controlbox and toggle is always on the far right.

- Remove section on UMD
- Add section explaining how to override templates
- Add overrides example to the relevant section
- Mention composition to add methods to existing classes

- Upgrade to latest commit in Strophe
- Import individual Strophe dependencies
- Replace strophe plugins with code in Converse

Also fix issue where trimmed headline chatboxes don't show the proper
color

- Take locked_muc_domain into consideration in chatroom display name
- Use getDisplayName when rendering the heading name
- Give preference to bookmark name if it exists

* Mention plugins for OpenFire and Prosody
* Mention demos on conversejs.org

when receiving an `unavailable` presence for ourselves.