Decoder : Add a live decoder using Gstreamer alsasrc
LiveDecoder : first prototype for a live decoder. The process can be interrupted by pressing CTRL+C two times
LiveDecoder : Add doc + doctest example
split decoder modules
encoder: rm core from init
fix fft_size arg for spectrogram
fix division from future (explicit import in EACH module)
add __future__.division to LiveDecoder also
Merge branch 'live' into dev

Conflicts:
	tests/test_decoding.py
	timeside/decoder/core.py