Fix configuration script for OSX library extension
Fix configuration script for OSX library extension

Get the shared library extension from the egspp_*.conf specifications
file, instead of assuming ".so".

When assessing whether egs++ is installed, the finalize script assumed a
".so" shared object extension, but on OSX it is ".dylib" instead.
Consequently compilation of egs++ codes was skipped on OSX.

In passing, add egs_cbct, egs_chamber and egs_fac to the list of egs++
codes variable, cpp_user_codes.

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