Free merger memory

ld2dap/Merger.py

@@ -41,9 +41,15 @@ class Merger(Filter):
             stack.end += offset
             metadata.append(stack)
 
+        self.free()
+        self.second.free()
+
         for output in self.outputs:
             output.process(data, [x.copy() for x in metadata])
 
+    def free(self):
+        self.data = self.metadata = None
+
     class SecondInput(Output):
         def __init__(self, merger):
             super().__init__(self.__class__.__name__)
@@ -55,3 +61,6 @@ class Merger(Filter):
             self.data = data
             self.metadata = metadata
             self.merger.process()
+
+        def free(self):
+            self.data = self.metadata = None