doc: Remove unused commands and packages.

* epsfig is unused since we're using graphicx+epstopdf.
* The wrapfig package does not appear used anywhere.
* Changes to the @ character code seem unnecessary.
* Also, move packages together instead of between command definitions.
doc: Really center front page figure.

Use zero margin and fills to ensure it's really in the centre. That
should eliminate the need for any adjustments if the figure changes
size. It does shift down a bit, but I think it looks better this way.