Updated README.md

Added "touch" config property

For backward-compatibility, add a new 'fragments' property to the
fragmentshown and fragmenthidden events. The 'fragment' property still
returns the first fragment.

Previously navigatePrev() was changing indexh and indexv; instead should
call slide(h, v) and let it change indexh and indexv.

They looked a little wonky if you used a G or a Y.

update serif (controls, attribution URL, and fix <a> elements)

The Serif theme was a little flaky previously