Improve the AhdcExtractor class (decoder int the GUI)

[ftouchte]

[ftouchte]

1. Change the way the integral is computed or change the representation of the integral (green area).

$$ \mbox{integral} = \sum{\mbox{adc}} $$

while is represented

$$ \mbox{integral} = \sum{(\mbox{adc} - \mbox{adcOffset})} $$

[ftouchte]

2. Add more protection. Make the attributes privates.