Add language dropdown to maze and turtle.  Improve initial layout of puzzle blocks.  Allow enter/esc/space to close puzzle help.  Upgrade URL param handling functions in apps/common.js.  Start migration from "Blockly > App" to "Blockly : App" (solves RTL headaches).
Review URL: https://codereview.appspot.com/10314043

git-svn-id: http://blockly.googlecode.com/svn/trunk@1075 c400ca83-b69d-9dd7-9705-49c6b8615e23