add footprint library expects 2 directories

In 20060822 if you try to add a directory via the
file-->preferences-->libraries ... the footprints will
only show up in the library browser if they are in a
subdirectory of the one you've added.

i.e. the fp library browser finds footprints in a
subdirectory of the one you've added but not the
_actual_ directory you've added.

I am unable to add a library manually to system-wide
pcb scripts using Pcb.elementPath ... and there is
something about these libraries getting added at
compilation. So I don't know if you can still add a
library this way. At any rate, I wasn't able to
simulate the above behavior manually.