Removed some unnecessary assert() calls

git-svn-id: http://svn.osgeo.org/postgis/trunk@11077 b70326c6-7e19-0410-871a-916f4a2858ee
Additional calls to assert() and better checking of out-db raster bands

git-svn-id: http://svn.osgeo.org/postgis/trunk@11078 b70326c6-7e19-0410-871a-916f4a2858ee
Fixed dimension error of bands when using ST_Tile on out-db rasters.
Ticket #2198

git-svn-id: http://svn.osgeo.org/postgis/trunk@11079 b70326c6-7e19-0410-871a-916f4a2858ee