Soft upgrade: avoid drop/recreate of aggregates that hadn't changed

Generate raster upgrade script using postgis_proc_upgrade
Add 2.2.0 availability for new raster aggregates
See #2560

git-svn-id: http://svn.osgeo.org/postgis/trunk@12243 b70326c6-7e19-0410-871a-916f4a2858ee