Don't limit QPT to two qubits

--CAR
Handle variances in QST

--CAR and BRJ and MPS
Load variance data if available.

--CAR and BRJ
Save variance data along with mean

--CAR and BRJ
Be more accepting of noise in slope fitting.

--CAR
Adopt new measurement length from channel paraemeters

Also allow user to not create file (if it has been created in QGL e.g.)

--CAR
Pulll out the mean data in pulse calibration

We have to specify as there is also variance data.

--CAR
Update for PyQLab naming.

--CAR and BRJ
Add option to create sequence

--CAR