Integrate build script with Extension Auto-installer
Add an option for disabling/enabling animations only on some domains

Closes #10.
Add an option for playing on hover as soon as the image loads
Add an option for not stopping hover-play when hovering another image
Don't catch Shift+M for editable targets
Prevent default even for Shift+M
Don't act on image loads after shutdown
Reorder + reword options
Allow changing the keyboard shortcuts
More tumblr hacks
1.2