some downstream applications need to know which sub-commands
may alter the index. this new function allows them to be
identified, while not prescribing any particular behavior.
our policy has been to vendor the libraries required for the
command-line portion of the bleve command-line tool. this
included spf13/cobra etc, unfortunately we missed this library
as it is only required for windows users.
bleve check was a consistency checking tool originally developed
as a part of cbft. currently it checks that the term dictionary
counts match the number of postings for the term. in the future
additional checks could be added. this tool has been back
ported to bleve as we've now adopted a single common tool for
both cbft and bleve.