On appearance table of contents now scrolls to reflect onscreen section.

TOC now limits top and bottom cells from scrolling past midscreen.

Scrolls to last section after rotate.

Partial implementation of web view scale and skew to side when TOC shown.

Partial implementation of vertically stacked image layout.

Refactor and bug fixes.

Change-Id: Iaf96db1de2696ce6a10c76216215e0e4fab68a43