Update to Strophe 1.2.16

They're not included in the repo and this makes it more difficult for
people to try Converse locally

Previously the Promise.all made it all-or-nothing, now it'll return
partial matches as well and it'll also log error stanzas.

Also fix if/boolean bug when checking whether we should automatically
register

This is to avoid having a stale/inaccurate MUC features list when
reopening a previously closed MUC

in which case a disco query is not sent out again because we still have
it cached.

This will cause their nick to be registered (if Prosody supports it).

Also expand and fix the associated test.

By doing so we create a new DiscoEntity for the room, which allows us to
query for features via the disco API.

We also avoid duplication of functionality between converse-muc and
converse-disco

Also add new API methods which return features and XEP-128 fields.

- Move `getDefaultNickName` to the model and rename to `getDefaultNick`
- Let `checkForReservedNick` return a promise and save `nick` once received
- Updated `openAndEnterChatRoom` to wait appropriately and remove presence-wrapper
- Update tests to wait appropriately
- Remove presence-wrapper in `getRoomFeatures`

See https://xmpp.org/extensions/xep-0045.html#register

As soon as a chatroom from that domain is opened and if the MUC supports it.

Looks like Chromium strips the forward slash from `<br/>` when printing
innerHTML.

Currently translated at 75.5% (256 of 339 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/pl/

Currently translated at 65.7% (223 of 339 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/nb/

Currently translated at 100.0% (339 of 339 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/hu/

Currently translated at 100.0% (339 of 339 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/cs/

- Avoid registering `sendChatState` twice as handler.
- Avoid sending out a CSN right after sending out a message