Initialize using Firefox Jetpack SDK
Add alt+ctrl, alt+shift, cmd+ctrl and cmd+shift modifiers

Now you can use combinations of modifier keys as Paper modifiers. That
can be useful when you don't want to lose Firefox default modifier
functionality.
Define Paper functions right in exports object
Add new options (notifications and right-click)
Fix Facebook URLs, fixes the bug reported via e-mail

Facebook prefixes URLs inside the site with facebook.com/l.php?u= to
redirect to the page that warns you about possible dangers ahead.

Before sending URL to Instapaper we need to get rid of this prefix first.