remove the benchmark directory from the main qutip repository (they are now available in the qutip/qutip-benchmark repository)
Merge pull request #217 from jrjohansson/remove-benchmark

remove the benchmark directory from the main qutip repository
made the use of progress bar in mcsolve optional. closes #219
Merge pull request #220 from jrjohansson/mcsolve-pg-optional

made the use of progress bar in mcsolve optional. closes #219
Updates to SS module
Added docstrings to build_preconditioner
Merge branch 'correlation_2op_1t_fix'