Allow to set the randomseed via parameter (or something)

[andresailer]

k4MarlinWrapper/k4MarlinWrapper/src/components/MarlinProcessorWrapper.cpp

Line 163 in 35f8132

marlin::Global::parameters->add("RandomSeed", {"123456"});

Also check that this actually does something.
On first call to ProcessorMGR::instance() the processormgr is instantiated, which also instantiates the EventSeeder, which takes the randomseed from the global parameters. So this RandomSeed could already be used, but I don't remember any more