Beginnings of QLText

Checkpointing, but have made significant progress.

Introduced the QLText type, and the beginnings of the QLParser.

Changed the TextTypes to be based on QLText (as they should be) instead
of Wikitext.

Introduced PlainTextType, for Properties that should have unvarnished
plain text.  This is a middle ground between Name and QLText.
Fixed a bug in list rendering

It was double-Wikitexting the contents of a List.
Replaced OneColl with Some

Realized that my hacked OneColl did have a cognate in the Scala standard
library -- while I think of Some as a detail of Option, it actually has
the right connotations.
Collections are now always Iterable

Another long-desired improvement: added a view bound requiring that the
underlying type of a Collection can be implicitly converted to Iterable.
This means that we should now be able to use Iterable methods on
Collections, without needing messy switches and things.  This will be
crucial for working with QL.
More Collection simplifications

Now that Collections are always Iterables, the doFirst and doIsEmpty
overrides are unnecessary.
Progress towards adding Context

Checkpoint before I do something stupidly dangerous.  We've pushed the
notion of "context" into PropAndVal.render.  Next, we're going to push
it further down the chain.

Also, fixed a QLText vs. PlainText bug.
Added the Iterable bound to Property's Collection

Involved a hack or two that I am not overjoyed about, but seems to work.
Links now work!  Yay!

Pushed the concept of Context all the way down to PType.  Made LinkType
context-sensitive, which allows it to render properly as a Wikitext
link.