Okay, no more async fiddling.
Source image from a element instead of img. Disregard the latter completely.

- move background-position to css
- stop mangling img links at all
- move /sxxx-foo/ regexp to gcu object
Simplify url mangling, get rid of webpsrc in favor of plain href.
Cleanup.
Adjust gallery fixer.
Update README.
Cleanup.
Add plusone button. Move attribution to the right.