Test data was taken from the Go distribution, which was in turn taken from the
testregex test suite:

  http://www2.research.att.com/~astopen/testregex/testregex.html

The LICENSE in this directory corresponds to the LICENSE that the data was
released under.

The tests themselves were modified for RE2/Go. A couple were modified further
by me (Andrew Gallant) (only in repetition.dat) so that RE2/Go would pass them.
(Yes, it seems like RE2/Go includes failing test cases.) This may or may not
have been a bad idea, but I think being consistent with an established Regex
library is worth something.

Note that these files are read by 'scripts/regex-match-tests.py' and turned
into Rust tests found in 'regex_macros/tests/matches.rs'.