[ee] DIS hadron rate

[Zhiwen Zhao]

Hi, Xiaochao

Here is the comment in the original Wiser routine

Subroutine WISER_ALL_SIG(E0,P,THETA_DEG,RAD_LEN,TYPE,SIGMA)
!------------------------------------------------------------------------------
! Calculate pi,K,p  cross section for electron beam on a proton target
! IntegrateQs over function WISER_FIT using integration routine QUADMO
! E0         is electron beam energy, OR max of Brem spectra
! P,E       is scattered particle  momentum,energy
! THETA_DEG  is kaon angle in degrees
! RAD_LEN (%)is the radiation length of target, including internal
!                (typically 5%)
!               = .5 *(target radiation length in %) +5.
!       ***  =100. IF BREMSTRULUNG PHOTON BEAM OF 1 EQUIVIVENT QUANTA ***
! TYPE:     1 for pi+;  2 for pi-, 3=k+, 4=k-, 5=p, 6=p-bar
! SIGMA      is output cross section in nanobars/GeV-str
!------------------------------------------------------------------------------

I see everyone has a little different wrapper to calculate rad_len for 
different nuclei target and use it as an input for the wiser function

I see your fortran code and Xins fortran code just calculate He3 or LD2 
target rad_lend and call wiser directly.

When Lorenzo implement this into current C++ event generator, rad_len is 
calculated and then wiser code is called randomly by chance of 
proton,neutron ratio in the nuclei with pi+ pi- switched for proton and 
neutron.

Zhiwen