The ChatBox.show() method was being called for every invocation, 100ms after
the fact, instead of it being called only once.
Fixed that and also changed to call it at the start.
First component to remove is MUC which was moved to src/converse-muc.js
The components are written as plugins and use converse.js's plugin machinery.
Update the plugin docs somewhat with new insites found while working on the muc
plugin.