Describe the bug
A message such as

> > a
> > b
> c
d

or

> > > a
> > b
c

should display quote levels going multiple lines, but only the first line has multiple levels, and only the first level spans multiple lines.

To Reproduce
Steps to reproduce the behavior:
Send (or receive) one of the above blocks as a message.

Expected behavior
Second-level quotes (and more) should be able to span multiple lines.

Screenshots

Environment (please complete the following information):

• Desktop
• Browser: Firefox
• Converse.js version: both v10.1.6 and current master (04c3753).