Added dual-layout support to comparative taxa summary plots.

When comparing self versus other taxa summary plots, the layout of the page can now be toggled from horizontal to vertical (and back again). The page defaults to a horizontal (i.e. side-by-side) layout. Vertical layout is provided for users who do not have wide enough displays.

A loading screen is provided when first accessing the page as it can take a couple of seconds to load everything when hosted on the web (the taxa summary iframes are pretty huge).

This resolves issue #60.