Implement NoteCommit

sapling_notes.py

@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+from sapling_pedersen import windowed_pedersen_commitment
+from sapling_utils import i2lebsp
+
+def note_commit(rcm, g_d, pk_d, v):
+    return windowed_pedersen_commitment(rcm, [1] * 6 + i2lebsp(64, v) + g_d + pk_d)