NumPy lstsq rcond deprecation

[moorepants]

/home/moorepants/src/GaitAnalysisToolKit/gaitanalysis/controlid.py:489: FutureWarning: `rcond` parameter will change to the default of machine precision times ``max(M, N)`` where M and N are the input matrix dimensions.
To use the future default and silence this warning we advise to pass `rcond=None`, to keep using the old, explicitly pass `rcond=-1`.
  x, sum_of_residuals, rank, s = np.linalg.lstsq(A, b)