Evaluated Pion-Nucleon Cross Section Data Directory

Alekseev ea PhysRevC91:025205,2015
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Authors: A.Afanasev, W.Briscoe, and I.Strakovsky
        (revison 4 February 2018)

Evaluated cross section data for pion-proton

-- pip_el.dat - pi+p elastic 
-- pip_in.dat - pi+p inelastic
-- pim_el.dat - pi-p elastic
-- pim_in.dat - pi-p inelastic
-- pin.dat    - pi-p-->pi0n CXS
-- pie.dat    - pi-p-->etan

Add data format is G4VPhysicsVector compatible

Kinetic energy in MeV and cross section in millibarns 
