- add processing pipes support, using ProcessPipe and operator overloading

- add processing pipes support, using ProcessPipe and operator overloading
- add tests/api/test_pipe.py and rename tests/api/test.py to test_lolevel.py
- remove all buffersize constraints in core/api
- replace IProcessor.set_input_format() with setup(), which also resets the processor
- suppress IProcessor.input_format()
- replace IProcessor.output_format() with channels() and samplerate()
- remove IGrapher.set_nframes(), this is implementation specific
- add short guitar.wav (sweep samples drives my crazy ;)
- shorten example processor names (GainEffect -> Gain, etc...)