LIBKML: add layer creation options to generate a LookAt element at layer level

git-svn-id: https://svn.osgeo.org/gdal/trunk@26919 f0d54148-0727-0410-94bb-9a71ac55c965
LIBKML: add checks for ATC 38: LookAt

git-svn-id: https://svn.osgeo.org/gdal/trunk@26920 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_travis_macosx