Resolve "Operation Replacement in a SFG"

Added method with tests for replacing multiple operations in a sfg with another operation with the same amount of input / output ports. Closes #17

b_asic/core_operations.py

@@ -235,8 +235,8 @@ class MAD(AbstractOperation):
     TODO: More info.
     """
 
-    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
-        super().__init__(input_count = 3, output_count = 1, name = name, input_sources = [src0, src1])
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, src2: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count = 3, output_count = 1, name = name, input_sources = [src0, src1, src2])
 
     @property
     def type_name(self) -> TypeName: