VRT: implement heuristics to determine if GetMinimum()/GetMaximum() should use the implementation of their sources of not. Can be overriden by setting VRT_MIN_MAX_FROM_SOURCES = YES/NO (#5444)

git-svn-id: https://svn.osgeo.org/gdal/branches/1.11@27542 f0d54148-0727-0410-94bb-9a71ac55c965
JP2KAK: fix bug in vsil_target::end_rewrite() that prevented TLM index to be generated (#5585, patch by plroit)

git-svn-id: https://svn.osgeo.org/gdal/branches/1.11@27543 f0d54148-0727-0410-94bb-9a71ac55c965