Fixed problem when running multi threaded

[VinzenzBildstein]

• made HistoManager a normal class, not a singleton
• allocate HistoManager in RunAction constructor, i.e. for each thread
• EventAction uses the HistoManager of the RunAction that was passed to the constructor
• only output the start of run message for master thread, first slave thread, or if running in serial mode

Other fixes:

• changed seed to G4long (at least 32 bits)
• always delete visManager, not just in interactive mode, since we always allocate it (is this needed in batch mode?)
• removed creation of histograms, the new work flow is to use NTuple2EventTree and proof to create histograms