Updated Module#const_defined? specs for ::Name.
Updated Numeric#quo specs for calling #to_r.
Fixed IO.readlines spec.
Revert "Moving encode option spec to shared example, because both IO.write and IO.binwrite must support this option."

This reverts commit f32725141a63a621b771755dc50ec107db0324d6.

Conflicts:
	core/io/shared/binwrite.rb
	core/io/write_spec.rb