r1655: * Added udeb support, as pioneered by di-packages-build. Understands

r1655:    * Added udeb support, as pioneered by di-packages-build. Understands
     "XC-Package-Type: udeb" in debian/control. See debhelper(1) for
     details.
   * Dh_Lib: add and export is_udeb and udeb_filename
   * dh_builddeb: name udebs with proper extension
   * dh_gencontrol: pass -n and filename to dpkg-gencontrol
   * dh_installdocs, dh_makeshlibs, dh_md5sums, dh_installchangelogs,
     dh_installexamples, dh_installman, dh_installmanpages: skip udebs
   * dh_shlibdeps: skip udebs. This may be temporary.
   * dh_installdeb: do not process conffiles, shlibs, preinsts, postrms,
     or prerms for udebs. Do not substiture #DEBHELPER# tokens in
     postinst scripts for udebs.
   * dh_installdebconf: skip config script for udebs, still do templates