Extra line breaks are deleted from IMs

[dca00]

Describe the bug

Extra line breaks are deleted from IMs.

To Reproduce Steps to reproduce the behavior:

1. Enter new message that contains extra line breaks
2. Send
3. See that the sender's message log contains the message stripped of the extra line breaks

Expected behavior

The original formatting must be preserved for readability

Environment (please complete the following information):

• Desktop
• Browser Firefox]
• Converse.js version [e.g. 12.0.0]