experimental dense nullspace steadystate solver
experimental support for returning multiple steady states in steadystate_svd_dense
python3 fix
do not sort points when used to draw curves
add optional argument args to correlation functions, to be passed along to the dynamics solvers (e.g. to support list-string td formats)
added notebook for testing, comparing and benchmarking the steadystate solvers
improved performance of steady_direct_sparse
updated steadystate benchmark runs
minor performance improvement in steady_direct_sparse
rerun steadystate benchmarks
performance tuning
updated benchmarks and added profiling
FIXED: integer checks now also accept np.integer

Robert's steady state solver benchmarks would not work due to an int64
being past instead of a generic int.
steadystate solver using bicgstab + preconditioner
Merge branch 'master' of github.com:qutip/qutip
new steadystate benchmarks including bicgstab based solver of modified L rho = 0
Added subsystem_apply.py, which includes more efficient algorithms for the application of CPTP maps to individual components of composite quantum systems. Added super_to_choi.py, which contains a few utility functions for converting between different representations of CPTP maps. This is the first commit, likely much to do to improve efficiency, but basic functionality has been ensured.
Attempted PEP 8 compliance, n
Fixing accidental overwrite of super_to_choi.py caused by autopep8
Attempting to resolve conflict