Add option to set a random seed when smearing energies (and timings) in the DEE

[fhagemann]

Currently in the DEE, the default is to smear the energy and timing values using the FWHM in our calibration files.
In order to compare the results from multiple runs to each other, it would be nice to have an option to set the random seed to reproduce the exact same results in the exact same configuration.

[fhagemann]

Maybe this is already done (?):

nuclearizer/src/MAssembly.cxx

Lines 116 to 117 in 79ac091

	// Fixed seed to reproduce DEE results
	gRandom->SetSeed(20170912);

Let me investigate if running the DEE multiple times will give the exact same result.

[fhagemann]

Ok, so if I run the DEE without multithreading and just with one instance, I end up with the exact same result.
If I run the DEE with multiple instances and multi-threaded, the results are different.

This could be avoided by setting a random seed for each event based on their event or assembly ID (+ some master seed), for example.