Added a multiply function (does 2 Expressions)

also added some sign things. For Sum expression to print, it is important that all of its components have a sign accessible from getSign()
Added a multiply function (bugs with 2 multexpressions)
Added multiply()

It will distribute.
Added divide
Added divide
Parser deals with spaces now
Fixed some extra () in toString

In the constructor add a false option to remove outside parenthesis
Fixed some extra () in toString
Merge Shared_Pointers

Conflicts:
	src/MultExpression.cpp
	src/MultExpression.h
	src/SumExpression.cpp
	src/SumExpression.h