Note that data provider authors will have to properly flesh out these
functions since I do not know how each provider calculates the number of
layer; except for the OGR provider which correctly returns the actual number
of layers. All other providers have hard-coded to always return "1".
Obviously that will have to be changed.
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@3832 c8812cc2-4d05-0410-92ff-de0c093fc19c
