Added raw HTML output.

 To enable, add `htmlRaw: true` to the settings, and start strings with `settings.htmlRawPrefix` (by default this is `<!--HTMLRAW-->`).

This is useful for providing a shell that also allows HTML output from the interpreter.
That HTML output can interact with the shell or link to other functions.

While ascii formatting requires interpretation to translate to CSS, raw HTML only needs a marker at the beginning of the "line" to indicate that the line's \<div/> should contain raw HTML. In this case, an HTML comment works and does not need to be removed from the string. The default HTML comment is "<!--HTMLRAW-->" but the user can change this in the settings.

Its kind of cool to "echo" raw html and get images, tables, and buttons in the "shell"!