Added string replacement function for future use

examples/music21_example.py

@@ -0,0 +1,15 @@
+from music21 import *
+from sardine import *
+from ziffers import *
+
+
+s = to_music21('i v vi vii^dim',time="4/4")
+
+s.show()
+s.show('midi')
+
+parsed = zparse('1 2 qr e 124')
+s2 = to_music21(parsed,time="4/4")
+
+s2.show()
+s2.show('midi')