Restore intensity variable to scans (#433)

This resolves #433 (closed).

Sim/Scan/AlphaScan.cpp

@@ -54,6 +54,7 @@ AlphaScan::AlphaScan(int nbins, double alpha_i_min, double alpha_i_max)
 AlphaScan* AlphaScan::clone() const
 {
     auto* result = new AlphaScan(*m_axis);
+    result->setIntensity(intensity());
     result->setFootprintFactor(m_footprint.get());
 
     if (m_lambda_distrib)