Implemented function that resolves an Action in a given State and returns the State that results.
Implemented the SearchNode and SearchProblem constructors, as well as an auxiliary method to determine whether or not a SearchNode is the root of the search tree.
Enforced object subclassing for SearchNode and SearchProblem and added a goalTest method for the SearchProblem, with corresponding unit test.
Added hash-bang for python and corrected the file documentation.
Added the hash-bang for python and updated documentation.  Also tried to fix some of the extraordinarily long lines of code to help with readability.
Added the (untested) General Tree Search algorithm, along with the corresponding auxiliary functions it uses.
Test for path_to