Ruby

[ruby/reline] Reduce direct references to Reline::IOGate
(https://github.com/ruby/reline/pull/566)

• Avoid referencing IOGate from IOGate classes

The only time those classes being used is when themselves being the IOGate.
So when referencing to IOGate, it's better to use self instead.

• Avoid referencing to IOGate from LineEditor directly

• Avoid referencing to IOGate from Core directly

• Reference to Reline.core directly

• Replace Reline::IOGate with Reline.core.io_gate