QL needs a match function

Summary: There are times when you really want a switch or match function. Just as a simple example, in the Respectful Calm Space, there are several functions that want to match on Character Gender and produce different Text as a result. This is classic "match" in the Scala sense, but you currently have to do it with annoying nested _if's.

Not clear at all what the syntax for this should be. Let's try to avoid making match too much of a special snowflake, but it is worth careful thought -- after all, we're delving into what in Scala becomes Partial Functions, which wind up as a core language mechanism. Being able to match on different Text inputs is good, as is matching on particular Links (which is what we have in this case), as is matching on the Type of the received value. And once we get into it, we probably want to be able to match on the value of a particular field buried inside of a Model Type (essentially the equivalent of Scala's unapply on case classes).

So spend the time to design the syntax for this sucker, and be open to it becoming a really important mechanism. We're a pure-functional language, so it's totally unsurprising that we would want this.