Feature:Multi-backend support

Kosmos currently comes with support for both IRC and XMPP (albeit hiding most of their complexity from the user). With Sockethub, it's very easy to add more protocols/APIs like for example Mattermost or Matrix, or even closed-source, centralized backends like Gitter, Slack, or Facebook Messenger.

We could also think about providing open-protocol gateways/bridges to the non-open ones instead of implementing their API directly (or use existing ones where possible).

Private servers/chat are planned to be implemented on top of XMPP, which is the most feature-complete (and extensible) messaging standard in existence today.

Notes

• https://xmpp.org/extensions/xep-0045.html
• https://help.hipchat.com/knowledgebase/articles/64377-xmpp-jabber-support-details
• https://slack.zendesk.com/hc/en-us/articles/201727913-Connecting-to-Slack-over-IRC-and-XMPP