Implement Module#initialize (15.2.2.4.31)
mrb_include_module support class and module
that not have methods each other
Move `Kernel.local_variables` to core.
Add 'Raise in rescue' test to exception.
Merge pull request #2296 from take-cheeze/core_local_vars

Move `Kernel.local_variables` to core.
Merge branch 'add-exception-test' of https://github.com/yui-knk/mruby into yui-knk-add-exception-test
correct comment; ref #2297
update raise in ensure test
Merge branch 'master' of github.com:mruby/mruby
move prototype of mrb_format() from error.h to mruby.h; ref #2274
Merge pull request #2295 from ksss/module-initialize

Implement Module#initialize (15.2.2.4.31)