text drawer should be enhanced for multi-qubit gates

[ajavadia]

What is the expected enhancement?

1. If I have a two-qubit box/gate and want to apply it to non-adjacent gates, the text drawer raises the following error:

VisualizationError: 'Text visualizaer does know how to build a gate with multiplebits when they are not adjacent to each other'

We just need to indicate/mark those wires that the gate is acting upon, and then it will be clear.

2. This raises another issue. The order of wires can be different when the gate is applied, so the drawer should reflect that.

So I think we should show something like this:

         ┌─────────┐┌─────────┐
q3_0: |0>┤0        ├┤1        ├
         │ My_gate ││         │
q3_1: |0>┤1        ├┤ My_gate ├
         └─────────┘│         │
q3_2: |0>───────────┤0        ├
                    └─────────┘

Here, "my_gate" is a two-qubit gate, with some internal definition.
It has been added to the circuit like this:

circuit.append(my_gate, [q[0], q[1]])
circuit.append(my_gate, [q[2], q[0]])

Note: this code is possible in PR #1816