Add BlockMeta

Currently derives Meta without overriding anything, but is registered
under its own type id.

malcolm/core/blockmeta.py

@@ -0,0 +1,6 @@
+from malcolm.core.meta import Meta
+from malcolm.core.serializable import Serializable
+
+@Serializable.register("malcolm:core/BlockMeta:1.0")
+class BlockMeta(Meta):
+    pass

tests/test_core/test_blockmeta.py

@@ -0,0 +1,15 @@
+import os
+import sys
+import unittest
+sys.path.append(os.path.join(os.path.dirname(__file__), ".."))
+import setup_malcolm_paths
+
+from malcolm.core.blockmeta import BlockMeta
+
+class TestBlockMeta(unittest.TestCase):
+    def test_registered(self):
+        block_meta = BlockMeta("name", "desc")
+        self.assertEqual("malcolm:core/BlockMeta:1.0", block_meta.typeid)
+
+if __name__ == "__main__":
+    unittest.main()