nishaChandramoorthy/s3: Differential CLV method

In this release, the differential CLV method (preprint available soon) has been implemented for all the maps under examples/. The method itself is written in dclvclv in the file src/clvs.py. All the figures in the preprint can be generated by using files of the form plot[name of map].py under `utils/'.

If you use this method, please cite Chandramoorthy, N., Wang, Q., An ergodic averaging method to differentiate covariant Lyapunov vectors, submitted.