Python3 support

[JPfeP]

Hello,

It seems that audiostream is not yet ready for python3. I tried to fix a few errors but then my knowledge found its limits.

1. In sources directory, two files have problems with arrays (waves.pyx and puredata.pyx):
   search for lines like that :
   buf = array('h', '\x00' * self.chunksize)
   It seems that this is easy to fix by just adding a 'b':
   buf = array('h', b'\x00' * self.chunksize)
   There are a few iterations only of them.

2. Then in waves.pyx there are a few uses of "next" that is no more valid in python3. I tried to change them with the new syntax but it was not sufficient or proper I am afraid.

[avour]

Nice work trying to port it to python3 which is very helpful by the why.
If the obj is an iterator the in python2 it will have a next() method but for py3 just use the built in next()
Py2
obj.next()
Py3
next(obj)

[JPfeP]

I have managed to fix all the errors for python3 on my local version (I am getting some sound), I am going to push all the changes gradually.

[tito]

I merged all PR, is it ok for you @JPfeP ?

[JPfeP]

Hi tito,

Yes, perfecto.

The multisin example would need py3 update too, but I don't have time neither motivation for this. The pd examples work fine.