[Feature #3300] onig_number_of_captures に相当するメソッド Regexp#ncapture

Feature #3300: onig_number_of_captures e$B$KAjEv$9$k%a%=%C%Ie(B
Regexp#ncapture
http://redmine.ruby-lang.org/issues/show/3300

e$B5/I<<Te(B: Makoto K.
e$B%9%F!<%?%9e(B: Open, e$BM%@hEYe(B: Low
e$B%+%F%4%je(B: core, Target version: 1.9.x

Regexp e$B$K!"e(Bonig_number_of_captures e$B$KAjEv$9$k%a%=%C%Ie(B
Regexp#ncaptures e$B$rDI2C$9$k%Q%C%A$G$9!#e(B