2572 Redundant link on Potential Matches page and general cleanup

http://code.google.com/p/otwarchive/issues/detail?id=2572

When there are multiple potential givers, we let the user choose to expand a list of them via JavaScript. But when the user had JavaScript off, this link did nothing. Now it won't be there for them.

This also cleans up the tab spacing and comments in the code, puts all the sections of the form in fieldsets and adds legends to make them more accessible and more visually distinct, and adds a helper to handle the fancy e-mail links we do for participants and their signups.