mruby API changes

mruby-incompatible-api-changes.md

(:zap: may break some mrbgems)

• change format of MRUBY_VERSION
  • https://github.com/mruby/mruby/commit/ac4443879a58ce1d38743360971582875bcc8500
• mruby.h includes mruby/version.h
  • https://github.com/mruby/mruby/commit/50ef284015604ae426e23a5bea47b077d9eae4da
• remove support for very old cygwin releases
  • https://github.com/mruby/mruby/commit/b7899aa6ee54783ebc30f0bbb19b93d314b4ff10
• add RUBY_ENGINE (C API)
  • https://github.com/mruby/mruby/commit/27dbcd0f0d6f6144d5d59d215131bdbafda14f46
• ⚡ add mrb_module_get / mrb_module_get_under
  • https://github.com/mruby/mruby/commit/d8a5f1205338f8ed664745ef74c825b74b9bb081
• change mrb_define_class (C API)
  • https://github.com/mruby/mruby/commit/4a2c37df935495fd612377d67bdba0582ad1813e
• ⚡ remove mrb_name_class
  • https://github.com/mruby/mruby/commit/5da7bd3a9133f03eb259fd9858cb08fa56bc53ac
• add MRUBY_RELEASE_NO (C API)
  • https://github.com/mruby/mruby/commit/56b5356f6bb56893e9bd73ec0e4a1daf15f35f7e
• add MRUBY_RUBY_VERSION and other constants (C API)
  • https://github.com/mruby/mruby/commit/95e2be6508257af3ed4989b39c02d281ae6c5330
• add mrb_str_new_lit (C API)
  • https://github.com/mruby/mruby/commit/ed1bf9aa809acfaa42deba222968224e6e9d7b3c
• add RUBY_VERSION to notify syntax compatible version
  • https://github.com/mruby/mruby/commit/5172f4797f9e8648260108a31bf13a5cf2b29555
• add Float#nan?
  • https://github.com/mruby/mruby/commit/7bf63c28769ebccb660294a38330a6abc3a22be1
• ⚡ clean up external symbols
  • https://github.com/mruby/mruby/commit/f2a62a74ed22a535ebea4dd71faf05bda6011fd4)
• ⚡ mrb_str_format() has moved to mruby-sprintf
  • https://github.com/mruby/mruby/commit/eaf445ea5c49ee286ca0b584387b50cfea63c60d
  • https://github.com/mruby/mruby/commit/bb25d42d0d23a2313c309b7f437299c0a095a4c5