2013-07-25  Tim Shen  <timshen91@gmail.com>

	Add documents and comments.
	* include/bits/regex.h: Documents and comments.
	* include/bits/regex_grep_matcher.h: Likewise.
	* include/bits/regex_grep_matcher.tcc: Likewise.
	* testsuite/28_regex/iterators/regex_iterator/char/string_position_01.cc:
	New.

From-SVN: r201244