Allow the directive to show multiple namespaces using two different
formats. The default is to merge all options in common groups and show
the groups in alphabetical order. The split-namespaces flag shows the
namespaces and groups in discovery order.
Change-Id: I91238a1c493cb055849821bb0273c487c20f0ecb
Signed-off-by: Doug Hellmann <doug@doughellmann.com>