Formatted messages are displayed literally

[redsky17]

Copied from mujx/nheko#457

Actual behavior
Formatted message is displayed literally.

Expected behavior
Formatting applied with the markup hidden.

Steps to reproduce
Send message with the following content:

Test list:

1. One
2. Two

What is displayed is this:

Test list:
<ol>
<li>One</li>
<li>Two</li>
></ol>

[redsky17]

After some testing and perusing of the code, it appears that this might only impact outgoing messages. Incoming messages are correctly formatted. This makes me think the likely culprit is the TimeLineItem function used for local messages, which starts on line 230 of TimeLineItem.cpp

[redsky17]

After even more investigation, it appears that the HTML between outgoing lists and incoming lists is slightly different. For example, here's the HTML associated with remote (incoming) event with the above text:

<p>Test</p>
<ol>
<li>One</li>
<li>Two</li>
</ol>

Here's the HTML when sending the same message locally (outgoing):

Test
<ol>
<li>One</li>
<li>Two</li>
</ol>

[redsky17]

It appears that this issue is due to intentionally trimming

tags in the markdownToHtml function. This was added here:
bf4d559
as a fix for mujx#438. I will need to do some additional investigating to figure out how to fix this and also keep mujx#438 closed.