Allow rendering messages as plaintext (#805)

Allow rendering messages as plaintext (#805)

* Parse room input from user id and emoji

* Add more plain outputs

* Add reply support

* Always include formatted reply

* Add room mention parser

* Allow single linebreak after codeblock

* Remove margin from math display blocks

* Escape shrug

* Rewrite HTML tag function

* Normalize def keys

* Fix embedding replies into replies

* Don't add margin to file name

* Collapse spaces in HTML message body

* Don't crash with no plaintext rendering

* Add blockquote support

* Remove ref support

* Fix image html rendering

* Remove debug output

* Remove duplicate default option value

* Add table plain rendering support

* Correctly handle paragraph padding when mixed with block content

* Simplify links if possible

* Make blockquote plain rendering better

* Don't error when emojis are matching but not found

* Allow plain only messages with newlines

* Set user id as user mention fallback

* Fix mixed up variable name

* Replace replaceAll with replace