added support for counting field in liouvillian operator
new module for counting statistics
added functions for computing pseudo_inverse
pep8 fix
Merge branch 'master' into counting-statistics
Merge branch 'master' into counting-statistics
changed function signature of countstat_current
improved pseudo_inverse and updated its docstrings
pep8 fixes
Resolving issue where LBFGSB terminates early when fid_err / grad NaN
Found to occur due to to larger elements in evo operators
when the alg choses (for some reason) large amplitudes
fix: upper and lower bounds now actually set when passed as pulseoptim method parameters
add: option to trace evolution: produce test_out file showing the evolution calculation steps at each iteration
fix/fudge: TraceDiff fid_err now defaults np.Inf when computed to NaN
fix/fudge: TraceDiff fid_err_grad now defaults np.Inf when computed to NaN
add: initial fidelity error and gradient calculated during dynamics.initialise_controls
change: stats object cleared each time Optimzer.run_optimization is called
change: result.stats is now a copy of the stats object
updated functions signatures
updated docstrings
reorganized imports
add countstat to  imports
docstring grammar fix
fix import errors
Merge pull request #292 from jrjohansson/release-3.1-code-cleanup

Release 3.1 code cleanup
use approach cleverly suggested by paul
pep8 fixes
code cleanup and docstring updates