Added extent() and contains() methods. Completed implementation of volume calculation for Boolean shapes.

• A new method extent() that finds the bounding box of the shape has been implemented for all classes derived from GeoShape. The calculations have been verified by comparison with the corresponding calculations in Geant4.

• A protected method diskExtent() has been added into GeoShape. This method is used or calculation of the extend of a tube, cone, polycone and torus.

• Added new method contains(x,y,z). This method returns true if the point belongs to the shape, false otherwise.

• Implemented GeoShape::volume() that calculates volume using MC method. It's allows to calculate volume of the Boolean shapes with good precision.