ParseXS/GenPod positional pod updates

["Ross McFarland" <rwmcfa1 neces com>]

just commited changes to ParseXS/GenPod in Glib that allows you to place
custom pod at just about any point in the autogenerated pod that you wish. see
the doc in GenPod for how to use it. it allows you to provide proper SYNOPSIS
and DESCRIPTION sections. it also allows you to completely override the SEE
ALSO and/or COPYRIGHT sections which can be useful under some circumstances.

i updated Glib/Gtk2 to use the new stuff where applicable. the new pod
keywords shouldn't bother anything if you're working with the old
ParseXS/GenPod they'll just be ignored one way or another.

the following things probably ought to be looked at:

have large amounts of pod about create customs incarnations of the types, i've
moved it to post_enums which places it as the last thing in the file before
SEE ALSO
  xs/GtkCellRenderer.xs
  xs/GtkTreeModel.xs

has a massive amount of general doc under the heading of description. i left
it that way, it probably ought to be split up and/or moved.
  xs/GtkDialog.xs

-rm