#2737 patch from Even Rouault: Upgrade of spatial_ref_sys.sql to EPSG v8.4, note also this update spatial_ref_sys to go back to using DATUM instead of towgs84 (back to  PostGIS 1.5 syntax), add new definitions, fix some existing ones.

git-svn-id: http://svn.osgeo.org/postgis/trunk@12622 b70326c6-7e19-0410-871a-916f4a2858ee
#2737 add back 900913 and update backup exclusion to exclude these. We still need to do somethng about upgrading spatial_ref_sys in general.

git-svn-id: http://svn.osgeo.org/postgis/trunk@12623 b70326c6-7e19-0410-871a-916f4a2858ee
#2737 typo

git-svn-id: http://svn.osgeo.org/postgis/trunk@12624 b70326c6-7e19-0410-871a-916f4a2858ee