Create data structure  TABLE, PIN, CELL
give an example main function parameter
Finish LoadLibrary
Fix return type to meet spec
Finish gate Exists and pin Exists function.
gate exist cost log n time.
pin exist cost log n time at gate search and then cost n time at pin search.
But feel free on n time due to small n at each gate. (no more then 10 generally)
Update the definition of getFunction.
Old definition is unclear on returning empty string. It will cause misunderstanding whether gate exists.
REASON: The input of a standard cell library is empty function.
New definition will return whether the gate exists. If exists, then function(reference string) will give the function of the pin.
set a compute rise transition example at main function
Define private pinExists to check pin before computation.

Define compute function that function only handle with table.
Assign compute task to compute function.(Decouple with rise/fall delay/transition status.)
Simple version on compute table.
Catch the worser result that both index are just larger than input parameter.