Update /challenge to /challenges where missed.
Clean up mist.ejs
Add simple error page.
Add Challenge to title of view-challenge pages.
Support viewing challenges by name and id
Update challenge gallery to use names rather than ids
Merge branch 'master' of github.com:GlimmerLabs/MathOverImages

Conflicts:
	Site/functions/challenge.js
	Site/views/view-challenge.ejs
Clean up mist-functions.js (slightly)

* Add some comments.  (More needed.)
* Move expToRGB from mist-render.js to mist-functions.js.
Remove log message from imagepage.js
Minor change to animation

* Use requestAnimationFrame rather than setTimeout.
Update date formatting in comments.
Add code for comparing functions.
Made four-wide gallery work.
Use four columns in challenges
Merge branch 'master' of github.com:GlimmerLabs/MathOverImages
Reformat resolution slider