Add *preliminary* release notes for GDAL 1.11

git-svn-id: https://svn.osgeo.org/gdal/trunk@27027 f0d54148-0727-0410-94bb-9a71ac55c965
OpenFileGDB: relax constraint on content of a .gdb.zip file

git-svn-id: https://svn.osgeo.org/gdal/trunk@27028 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_mingw