Merge pull request #2 from yuanchao/master

* Adding pitch detection via pymir builtin function
Added document about the workflow
linne-tuner : It will create sound.csv if it is missing
Added bin/linne-extract-wav : Extract the column from sampling csv and convert to wav file
labelfile.py : Report error if the file format is invalid
tuner.py : Prevent to update the threshold value if the data list is empty
sound.py : Supported to initialize attribute in constructor
linne-tuner : If the phonetic symbol is not found in sound.csv , it will add to the file automatically
phonetic/ipa.py : Changed the breakdown() and toLabel() function that will only process CV instead of every symbol
Added Ipa.simplifySymbol() -  Simplify vowel or consonant for sound table for matching

sound/table.py - The key will call Ipa.simplifySymbol() for simplifcation before access
tuner.py : Added ZCR and STE filter
Merge pull request #2 from benlau/master

Merge from up stream.