renewed experiments for HTML5DownloadSave

see saving.js: recreateOriginal() for generating/fixup of HTML source
from browser memory image...
more work on recreateOriginal()

eliminates differences from original file (testing in Chrome currently,
other browsers may need additional tweaks)
code cleanup recreateOriginal()
fix HTML5DownloadSave for firefox

In Firefox, the link element needs to be attached to the DOM before
calling the .click() handler
allow saving from anywhere

changes made online can be saved locally via the new HTML5 download
fallback handling.
update version/date for TW280b1
Merge pull request #130 from ericshulman/master

Initial implementation of HTML5 Download Saving