                       Changes in version 0.18.6                        

  - filter parameter added to bb_aadc_source() so that a metadata record
    with multiple data sets attached to it can be reduced to just the
    data set(s) of actual interest, if needed
  - a data source that obtains its files from S3 storage can now have
    multiple buckets in a single source

Breaking changes

  - bb_data_source_dir() can now return a vector of multiple paths
    (rather than a single string) for certain data sources
