Implemented equals tests in ActionTreeTester.
Added a couple of lines of comments to the equality test in TreeTester.
Fixed a bug in ActionTree's hashCode (style was converted from an int to
an Integer to support setting as null, so it needed a null check in the
hashCode).
Implemented the copy tests for ActionTreeTester.
Added a few more lines of test code to TreeTester.
Fixed some equality related bugs in ActionTree.