Fix segfault where metadata values weren't being nullchecked properly during conflict resolution. Exposed by #5069

git-svn-id: https://svn.osgeo.org/gdal/branches/1.10@25976 f0d54148-0727-0410-94bb-9a71ac55c965
 #4745 KML Superoverlay hybrid jpg and png output. (auto_format_no_empty_tiles.3.patch)
Conflicts:
	gdal/frmts/kmlsuperoverlay/kmlsuperoverlaydataset.cpp
Expand KMLSuperOverlay tile size to 512 < side < 1024px rather than 200 < side < 400px
Better support for writing RATs #4903 (4903.3.diff):

 * Write RATs for Imagine/HFA output by default
 * Copy RATs during gdalwarp file-creation as well.
 * Copy RATs during GTiff CreateCopy() (ie. gdal_translate) as well.
 * Copy RATs during gdal_translate VRT-path as well.
Remove stupid duplicates c/- patch. Add non-nearest resampling detection for RATs to gdalwarp.
Reduce PCT size to RAT size when building the color table. Fixes issues (64K palettes) when using GTiffs to move RATs about

Conflicts:
	gdal/frmts/hfa/hfadataset.cpp
Revert "Remove stupid duplicates c/- patch. Add non-nearest resampling detection for RATs to gdalwarp."

This reverts commit ccbc64c3857b4b8e87d5a3791bf51be1fae14246.
Revert "Better support for writing RATs #4903 (4903.3.diff):"

This reverts commit 262f4aae6471adda54a723cb8ff7b2da0640199b.
Better support for writing RATs #4903 (4903.5.diff):

 * track thematic/athematic RAT type
 * Write RATs for Imagine/HFA output by default
 * Copy RATs during gdalwarp file-creation as well (if using nearest).
 * Copy RATs during gdal_translate VRT-path as well.
 * but, discard RATs if the operation makes them invalid