Incorporate changes from gh-pages branch.
Forward progress on forms chapter.
Added regex visualization/tester.
Pulled out regular expression interactive into snippet.
Finally wrote an introduction (first draft)
Intro tweaks, more forms.

Forms is getting long. May have to break it into two chapters.
Finished form chapter (whew!). Started on Canvas.
Canvas chapter, added interactive sandboxes.
Refactored the MetaCanvas out.
Canvas progress, added intermission entries to ToC.
So much more canvas. Almost done.
That's a wrap on Canvas.
Merge remote-tracking branch 'origin/master' into gh-pages
Built pages.