Add virDomainCheckpoint APIs

Copies heavily from existing virDomainSnapshot handling, regarding
what special cases the generator has to be taught and what overrides
need to be written.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

libvirt-override-virDomainCheckpoint.py

@@ -0,0 +1,19 @@
+    def getConnect(self):
+        """Get the connection that owns the domain that a checkpoint was created for"""
+        return self.connect()
+
+    def getDomain(self):
+        """Get the domain that a checkpoint was created for"""
+        return self.domain()
+
+    def listAllChildren(self, flags=0):
+        """List all child checkpoints and returns a list of checkpoint objects"""
+        ret = libvirtmod.virDomainCheckpointListAllChildren(self._o, flags)
+        if ret is None:
+            raise libvirtError("virDomainCheckpointListAllChildren() failed", conn=self)
+
+        retlist = list()
+        for chkptr in ret:
+            retlist.append(virDomainCheckpoint(self, _obj=chkptr))
+
+        return retlist