Enumerate and rethink the prettify class category usages

Evaluating how to display code samples in my new website design.  It's not just Rebol code, so having a generalized system would be nice.  Thought I'd look at what you'd started here...

I went in and enumerated all of what Google Prettify offers.  Turns out you really can make as many classes as you want, they just standardized some of them... and if you want your stylesheet to work you should use styles other people know about.

As "literal" means "constant" in their vernacular, lit-word! shouldn't be a 'lit'.  @rgchris doesn't distinguish between the color of string literals and other kinds of literals, except he colors tags in cyan.  There is an html tag "standard" in Prettify so I used that.

I punned "attribute value" as refinement, but couldn't figure out how to get refinements to only happen when the term started with a slash.  *(Though being RegEx, "couldn't figure out" = "first thing I tried didn't work and I didn't want to try anything else because I cannot stand RegEx".)*  There is a similar problem happening with the keywords registering when they are part of a path.

I also couldn't figure out how to get "Red/System" to identify as the custom HDR type.  `Red\/System` didn't seem to do the trick.

There isn't really any "punctuation" in Rebol, So I just threw it onto the `#!` thing you had as a comment.  Kind of superfluous, just something to think about...