[MD]: - Moving most part of the auxiliary info stuff to a separate internal class (NetCDFIndexer)
 - Allowing external data dir config where to put auxiliary files: -DNETCDF_DATA_DIR env variable
 - checking whether the netcdf file is more recent than the available auxiliary files (still need to be improved... adding some locking)
Merge branch 'multidim' of https://github.com/geosolutions-it/geotools into multidim