zGui: huge re-style review to comply Pyhton code style

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler: skip interleaved channel on all channel view

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler: fix minor graphical bugs/issue

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler: comply with PyZio 0.4a, and remove useless import

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
GUI: use Plot object directly in the GUI

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler.py: Plotting data in a different function

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler.py: use class variable for colors

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler.py: introduce use of multiprocess for block acquisition

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler.py: use variable pointer instead of array index
ZioGuiAcquisition.py: new object to handle acquisition

Each time you create an instance of this object it starts to acquire
immediately until you set the stop_event flag. This object communicate
with other objects with the Queue object.

In zGui this class is invoked as a different process

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
ZioGuiHandler.py: use ZioGuiAcquisition to handle acquisition

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>