QWellArray: removed unused destructor
QWellArray: Removed dead code
QWellArray: Removed QT_NO_MENU functionality

This fixes bug #265
Removed duplicated source listing of wellarray.cpp
SigSession: Tidied update_signals
SigSession: Added signal_from_probe
LogicSignal: Tidyup boost references
Added AnalogSignal::analog_data accessor function
Feed analog data into separate deinterleaved analog data objects per channel