The method ReadPDGTable of TDatabasePDG was setting the stable flags for all particles regardless of their width.

The value reported in the fLifetime variable of TParticlePDG is in seconds while in the documentation is was indicated in nanoseconds.

Particles with a width greater than 1e-10 have now the stable flag set to 1.

New functions added in the interface:

For activation of collecting TGeo tracks:

virtual void SetCollectTracks(Bool_t collectTracks);
virtual Bool_t IsCollectTracks() const;

For accessing the normal vector of the crossing volume surface on the geometry boundary:
```
virtual Bool_t CurrentBoundaryNormal(Double_t &x, Double_t &y, Double_t &z) const;
```