Rename re2_filter and re2_matcher to regexp_*

Working for replacing to oniguruma from re2.
Add --enable-re2 option to use re2.
Currently configure to use oniguruma by default.
Make regexp filter/match test not to include regex.h

googletest includes POSIX regex.h that conflicts
oniguruma definitions.
Implement oniguruma matcher
Add onig_filter template