Problem 908

In some simple examples run on slc3 G4IonTable::IsLightIon ends up eating most of the cpu due to too
many string creation
Although more modern compilers may mitigate the problem I wish to suggest to modify the code
as follows (I think that for all practical use cases a linear search is better than a binary one)

#include <algorithm>
G4bool G4IonTable::IsLightIon(G4ParticleDefinition* particle) const
{
  static const std::string names[] = { "proton", "neutron", "alpha", "deuteron",
                           "triton", "He3", "GenericIon"};

   // return true if the particle is pre-defined ion
  return std::find(names, names+7, particle->GetParticleName())!=names+7;
}