Merge branch 'jh/object-filtering'

In preparation for implementing narrow/partial clone, the object walking machinery has been taught a way to tell it to "filter" some objects from enumeration. * jh/object-filtering: rev-list: support --no-filter argument list-objects-filter-options: support --no-filter list-objects-filter-options: fix 'keword' typo in comment pack-objects: add list-objects filtering rev-list: add list-objects filtering support list-objects: filter objects in traverse_commit_list oidset: add iterator methods to oidset oidmap: add oidmap iterator methods dir: allow exclusions from blob in addition to file