Remove some C functions(only method substance and not provided as C API).
Add description to Object#respond_to? about NotImplementedError case(native or not)
Merge pull request #136 from sho-h/remove-some-c-functions

Remove some C functions(only method substance and not provided as C API).
Fix Object#respond_to? clang-impl/ruby-impl description
Merge pull request #137 from tbpgr/add_description_to_respond_to

Add description to Object#respond_to? about NotImplementedError case(nat...
Add comma for readability
Merge pull request #138 from utenmiki/add_comma

Add comma for readability
Fix Object.instance_eval to Object/BasicObject#instance_eval. (closes gh-131)
Unify Japanese. (refs gh-130)
def-expr returns the symbol of its name instead of nil since 2.1.0 like 56f26f7. (closes gh-130)