Add option to terminate search on first match

[bonanza123]

An option like greps "-m 1" option would be nice.

[gahag]

Sounds like a great idea! Pull requests welcome.

[aquac]

I guess if we have no additional switches enabled, in particular not -b and/or -v, then we have this case because it relies on is_match (and not find_iter)

[gahag]

Indeed, but it would still be nice to have a flag like grep's -m, which allows to limit to an arbitrary number of occurrences.