update default parameters + python updates

- by default ggwave will now output 32-bit float samples
- python samples no longer use numpy
- python test now decodes payload
- fix buffer overflow in receive.py example

examples/ggwave-py/receive.py

@@ -10,7 +10,7 @@ instance = ggwave.init()
 
 try:
     while True:
-        data = stream.read(1024)
+        data = stream.read(1024, exception_on_overflow=False)
         res = ggwave.decode(instance, data)
         if (not res is None):
             try: