Refacotr mrb_str_substr()
Refactor mrb_str_hash()
Refactor read_lineno_record_1() in load.c
Add Hash#keep_if
Merge pull request #2194 from suzukaze/refactor-string.c2

Refactor string.c
Merge pull request #2196 from suzukaze/refactor-load.c

Refactor read_lineno_record_1() in load.c
Merge pull request #2198 from suzukaze/add-hash.keep_if

Add Hash#keep_if