Interactive help for the Maze.  Removed most innerHTML calls.  Fixed layout bug in Maze if arrow charachters renter too large.

Review URL: https://codereview.appspot.com/13480043

git-svn-id: http://blockly.googlecode.com/svn/trunk@1319 c400ca83-b69d-9dd7-9705-49c6b8615e23