Add "b5" theme

configure

configure.in

themes/Makefile.am

themes/Makefile.in

themes/b5/Makefile.am

themes/b5/Makefile.in

themes/b5/README

themes/b5/bottom-active.xpm

themes/b5/bottom-inactive.xpm

themes/b5/bottom-left-active.xpm

themes/b5/bottom-left-inactive.xpm

themes/b5/bottom-right-active.xpm

themes/b5/bottom-right-inactive.xpm

themes/b5/left-active.xpm

themes/b5/left-inactive.xpm

themes/b5/menu-active.xpm

themes/b5/menu-inactive.xpm

themes/b5/menu-pressed.xpm

themes/b5/right-active.xpm

themes/b5/right-inactive.xpm