* Use the wrapper of rb_cObject instead of data access
* Replaced rest of extentions
* Updated the version guard for Data
* Added the version guard of rb_cData
Has been deprecated since 684bdf6171.
Matz says in [ruby-core:83954] that Data should be an alias of Object.
Because rb_cData has not been deprecated, let us deprecate the constant
to make it a C-level synonym of rb_cObject.