Improve console functionality: live filtering, colorization, layout.

This refactors console.js and index.html to add a few new enhancements:

- Live filtering (would resolve #232)
- Colorized output (by log type)
- Auto-scroll when you're at the bottom
- Rearranged the UI to fit settings, display, and the console on the screen without being forced off the page

Since one of the tests uses the raw console output as test assertions (which seems kinda nice), I added another console type: `raw`, which behaves as before (so you can still do assertions based on document contents); it's hidden by default.

I'm not overly attached to any of these changes, as some of them are aesthetic; feel free to ask me to change things around.