Revise calculation type 1 in g application
Revise calculation type 1 in g application

Adjust calculation type "1" to reach a desired accuracy "accu" in
muen_rho:

Original:  accu(muen) = sqrt(accu^2+accu^2/4)     = 1.1*accu
Revision:  accu(muen) = sqrt(3*accu^2/4+accu^2/4) = accu

The revised calculation type "1" is now independent of the number of
histories, and the target accuracy defaults to 1%. Also, clarify the
calculation progress messages, and introduce the possibility to further
optimize calculation type 1 in the MeV range.

mchamberland/EGSnrc,nrc-cnrc/EGSnrc,mchamberland/EGSnrc,mchamberland/EGSnrc,nrc-cnrc/EGSnrc,nrc-cnrc/EGSnrc,crcrewso/EGSnrc,MartinMartinov/EGSnrc,mchamberland/EGSnrc,MartinMartinov/EGSnrc,crcrewso/EGSnrc,crcrewso/EGSnrc,crcrewso/EGSnrc,mchamberland/EGSnrc,MartinMartinov/EGSnrc,MartinMartinov/EGSnrc,crcrewso/EGSnrc,mchamberland/EGSnrc,MartinMartinov/EGSnrc,nrc-cnrc/EGSnrc,nrc-cnrc/EGSnrc