Concurrency added and Graph structure changes
Bug fixes
Transition derivative to return the transpose matrix directly
Insignificant changes
Added a new class and some functions for optimization in matlab
Changed project structure and new package created for implementation of stochastic gradient descent
Minor changes
Minor changes
Revert "Merge branch 'untested'"

This reverts commit cdad0c399c4a97ec733b7c07c7991f9d505ba435, reversing
changes made to 3421d2ad49838d25506c779bc0fd6ae9d43bcd3c.