Cleanup VoronoiDiagramBuilder interface, add NEWS item (#627)

Cleanups involved removing all explicit "delete" calls trough
auto_ptr uses, moving some allocations from heap to stack and
reducing object copies.

git-svn-id: http://svn.osgeo.org/geos/trunk@3955 5242fede-7e19-0410-aef8-94bd7d2200fb
ignore generated svn revision header

git-svn-id: http://svn.osgeo.org/geos/trunk@3956 5242fede-7e19-0410-aef8-94bd7d2200fb