Shapefile internal API name changes

[Kralidis,Tom [Burlington]]

Devs,

FYI I've cleaned up the Shapefile API function names in
http://trac.osgeo.org/mapserver/changeset/7240 as per
http://trac.osgeo.org/mapserver/ticket/599

As the ticket indicates, the function names changed are not visible
directly to mapscript users, so there should not be any issues, but
heads up of this change in case anyone encounters problems.

..Tom