added useful .gitignore files

Geant4/G4global/.gitignore

+/G4global/
+/HEPNumerics/
+/management/

Geant4/G4graphics_reps/.gitignore

+/G4graphics_reps/
+/src/

Geant4/G4intercoms/.gitignore

+/G4intercoms/
+/src/

Geant4/G4materials/.gitignore

+/G4materials/
+/src/

Geant4/G4modeling/.gitignore

+/G4modeling/
+/modeling/

Geant4/G4parmodels/.gitignore

+/G4parmodels/
+/gflash/

Geant4/G4particles/.gitignore

+/adjoint/
+/bosons/
+/G4particles/
+/hadrons/
+/leptons/
+/management/
+/shortlived/
+/utils/

Geant4/G4physics_lists/.gitignore

+/builders/
+/G4physics_lists/
+/LHCb/
+/lists/

Geant4/G4processes/.gitignore

+/biasing/
+/cuts/
+/decay/
+/electromagnetic/
+/G4processes/
+/hadronic/
+/management/
+/optical/
+/parameterisation/
+/scoring/
+/transportation/

Geant4/G4readout/.gitignore

+/G4readout/
+/src/

Geant4/G4run/.gitignore

+/G4run/
+/src/

Geant4/G4track/.gitignore

+/G4track/
+/src/

Geant4/G4tracking/.gitignore

+/G4tracking/
+/src/

Geant4/G4vis_management/.gitignore

+/G4vis_management/
+/management/