Fixed mpl drawer output (#2061)
Fixed mpl drawer output (#2061)

* Updated the mpl drawer so that the output is no longer messy

* Renamed gate_index to gate_anchor

* Fixed off by 1 error - gates now begin in column 0 not 1

* Fixed linting

QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py