Refactoring

• /!\ Major refactoring for more pep8 compliance --> names of classes, methods and arguments have changed
• Added new method getChannelName4() for mdf4.x to only find mdf channel name (unique key within mdf class inherited from dict) based on name and source path or name (same name can be used in mdf file file but source paths or names shall be different, making it unique). Can be reused then with getChannelData4()
• Improved xml metadata parsing speed.

Fixed bugs related to
-nBytes calculation
-HL Block in VLSD data
-setup.py and cythonize
-channel by channel array reading implementation in python (fallback of dataRead)
-SD Block read of byte array type