History
+2019/03/22: add new options ONIG_OPTION_TEXT_SEGMENT_EXTENDED_GRAPHEME_CLUSTER and
+ ONIG_OPTION_TEXT_SEGMENT_WORD
+2019/03/21: PR #137: fix cross-compilation
+2019/03/20: update Unicode version to 12.0.0
+2019/03/17: add doc/SYNTAX.md
+2019/03/13: {n,m}+ and {n,m}? are possessive and reluctant range operator
+ in Perl syntax
+2019/03/04: fix #132: don't execute testp if ENABLE_POSIX_API == no
+2019/02/28: re-implement bytecode by using Operation struct
+2019/02/26: fix #130: Build error on UWP with VS2017
+2019/02/03: PR #128: regerror/toascii: do not attempt to serialize NULL pointer
+2019/01/30: Build breaks without autoreconf #73
+2019/01/02: fix #127: Windows VS 2008 build errors
+2018/12/19: fix #126: Unable to compile when USE_CALLOUT is not defined
+
2018/12/11: Version 6.9.1
2018/10/08: use ENC_FLAG_SKIP_OFFSET_XXX values