Remove requirement of recent env executable to ensure C++/Python unbuffered...

Remove requirement of recent env executable to ensure C++/Python unbuffered output; add env. var. to environment instead

tools/fnlosrc_install.csh

@@ -1190,6 +1190,9 @@ if ( $withpython ) then
    echo 'setenv PYTHONPATH '"${PYTHONPATHADD}" >> fnlosrc_source.csh
    echo 'export PYTHONPATH='"${PYTHONPATHADD}" >> fnlosrc_source.sh
    endif
+   # Unbuffered Python output to avoid mixing C++/Python
+   echo 'setenv PYTHONUNBUFFERED 1' >> fnlosrc_source.csh
+   echo 'export PYTHONUNBUFFERED=1' >> fnlosrc_source.sh
    echo ""
    echo "ATTENTION: PYTHONPATH environment complemented!"
    echo "   PYTHONPATH has been set to:"

v2.5/toolkit/src/fnlo-py-print.py

-#!/usr/bin/env -S python3 -u
+#!/usr/bin/env python3
 #-*- coding:utf-8 -*-
+### This shebang line only works with recent enough env version: !/usr/bin/env -S python3 -u
+### Set PYTHONUNBUFFERED environment variable instead to 1.
 #
 ########################################################################
 #