Support Default Foreground and Background headers

[Frieren360]

Micron allows you to set the default background or foreground for an entire NomadNet page using #!bg=X or #!fg=X. In the terminal nomadnet client, this works fine as long as it is not the very first line. Please could you add this to meshchat?

[RFnexus]

I'll update the JavaScript Micron parser to support those tags. Thanks for the reminder