Begin to add the explaination system of the expert system.

Not finished yet!
Next assignment:
1. expand the pattern tree(not, and, or node if need)
2. explaination interfaces
Add the explaination system of the expert system(Step Two)

Not finished yet!
Next assignment:
1. complete transferring node to string
e.g 'home' node(child-BColor) to "The cubie have #Back Color# is home'.
conflict resolve