buffer/Size: disable trigger while flushing

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
buffer/Size: more details on error

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
buffer/Overflow: more details about error and minor fixes

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
update is_device_ready() usage

Incompatible change was done to zio, so to PyZIO. Now is_device_ready()
timeout parameter must be written in milli-second

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

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