Update BinaryView Python context manager to actually release the BinaryView resource.

Author: bpotchik

python/binaryview.py

@@ -2605,18 +2605,25 @@ def __init__(
 		self._platform = None
 		self._endianness = None
 
+	def _cleanup(self):
+		if core is None:
+			return
+		for i in self._notifications.values():
+			i._unregister()
+		self._notifications.clear()
+		if self.handle is not None:
+			core.BNFreeBinaryView(self.handle)
+			self.handle = None
+
 	def __enter__(self) -> 'BinaryView':
 		return self
 
 	def __exit__(self, type, value, traceback):
+		self._cleanup()
 		self.file.close()
 
 	def __del__(self):
-		if core is None:
-			return
-		for i in self._notifications.values():
-			i._unregister()
-		core.BNFreeBinaryView(self.handle)
+		self._cleanup()
 
 	def __repr__(self):
 		start = self.start