Modular-Kicad milestone B), glamorous portions:

*) Eeschema can now show the footprint editor.

*) Eeschema can now invoke the footprint picker from the library part field editor.

*) KIWAY_PLAYER::ShowModal() takes aResultantFocusWindow that tells what window
   to give the focus to.  Required since frames are often near the top of the
   hierarchy and they are invoked by a peer, not a parent.