Switched save.html to use https

Needed for DropBox and Google Drive
Birds that leave box don't display hole background

Until they return to the box.
Updated demo page in intro talk
Added elementHTML URL parameter

If elementHTML=1 then element widgets with text display and update the
HTML. The default remains plain text.
Updated the 'future' slide in intro talk
Added browser warning to README
Merge pull request #136 from ToonTalk/master

Updating gh-pages to master