Add a --print-all-matched option.

The default behavior, to not print any matched lines, is unchanged.
Merge pull request #651 from yarikoptic/master

Merge of recent 0.8 (very minor changes) to establish the bridge for future easy merges of fixes from 0.8
Merge pull request #652 from hlein/master

ENH: Add a --print-all-matched option.
DOC: ChangeLog for gh-652
DOC: note to have release tagged by a signed/annotated tag

Came up in #650