Rename API mrb_str_cat2() to mrb_str_cat_cstr(). This is for naming orthogonality. mrb_str_cat2() is also left for backward compatibility.

Fix the type of value that is returned by bit shift expression.

Add configuration macro MRB_PARSER_BUF_SIZE.

add method(uniq, -, |, &, flatten, compact) of Array to mruby-array-ext

add mruby-hash-ext mrbgem, and method: Hash#merge!

add Enumerable#each_cons/each_slice/group_by

xquote operator

Add new API mrb_intern_cstr(). This is for naming orthogonality. mrb_intern is also left for backward compatibility.

Add an internal function intern_c(). It reduces function call parameter. For maintainability and performance.

bugfix escape charactor for Regexp class

Fix indentation in keywords

Update Travis CI build to install gperf

Add gem version to build summary

add mrbgem: mruby-enum-ext and some methods.