Pre button in editor

[LazyKarlson]

Button for

 HTML tag added to editor.
My VS Code add some spaces to code for readability thats why many changes in commit.
            

[LazyKarlson]

Please get rid of the unrelated formatting changes.

@Aivean Done!

[Aivean]

@LazyKarlson, did you test it?

I think the parser support should be more involved, as right now it will still perform all replacements inside the <pre> tag (like videos and mentions).

Additionally, regex is not the right tool to do html escaping here. Also, this logic shouldn't happen on the client. The user should see clear readable text inside the <pre> tag when writing/editing.

[maximt]

I think [code] tag will be more expected and more well-known by users.