PM code escaping

[d-dd]

Coded messages like &&& become escaped and turn into &&& when sent through PM's.

The preview shows &&& so it's a little bit confusing when it turns out different.

I'm not sure if escaping is intended, but if it is maybe the preview should also show it escaped. It's such a minor thing but though I'd point it out. 🍡 Might be related or duplicate of # #38 or #39.

[riipah]

Previews are always rendered with marked JavaScript library. Messages are rendered server-side using MarkdownSharp. Marked includes built-in HTML sanitizer, while MarkdownSharp doesn't. Instead, the HTML is sanitized using .NET's built-in library which probably encodes those ampersands. So yeah, it's related to both tasks, mainly #39, and should be fixed when that task is done.

Additionally, since Markdown isn't exactly a standard, two different libraries might produce different results, there's nothing that can be done about that. There's CommonMark project for standardizing the Markdown syntax, but it's not finished yet.