Change JavaScript and Python generators to be children of Blockly.Generator.  Significant simplification and makes Closure compiler happier.

R=spertus@google.com

Review URL: https://codereview.appspot.com/13740046

git-svn-id: http://blockly.googlecode.com/svn/trunk@1370 c400ca83-b69d-9dd7-9705-49c6b8615e23
Minor fixes to msg/messages.js and i18n/js_to_json.py in preparation for major changes.

R=neil.fraser@gmail.com

Review URL: https://codereview.appspot.com/13492046

git-svn-id: http://blockly.googlecode.com/svn/trunk@1371 c400ca83-b69d-9dd7-9705-49c6b8615e23
Added de.json, making de.js a generated file.
Made minor improvements to en.js and create_messages.py.
This command line was key to making the change:

cat de.js | sed -e 's/"/\\"/g' | sed -n "s/^Blockly.Msg.\(\w*\).*\s*=\s*'\([^']*\)';$/\"\1\": \"\2\",/p"  > ../json/de.json

R=neil.fraser@gmail.com

Review URL: https://codereview.appspot.com/13550050

git-svn-id: http://blockly.googlecode.com/svn/trunk@1372 c400ca83-b69d-9dd7-9705-49c6b8615e23