Also add a 'video games' species tag

This sets the unit that the attribute will be shown with. It
uses the same mechanism that's used to remember what units
you had selected.

It got mad if a layer was missing.

This way, people might actually read the instructions (:

Also fix the delete button appearing on page load

The ground now defaults to very-low, not bottom.
Zoom-on-add defaults to off.

This allows for multiple filters to be applied simultaneously. This commit
also moves some misc stuff, like the help and donate buttons, into a new
info menu. This also fixes touches outside of a popout menu not causing
the menu to close.