Add redirect_output configuration option

Add redirect_output configuration option that controls whether or not
the output of module command should be redirected from stderr to stdout.
Enabled by default. When configuration is modified it sets the
MODULES_REDIRECT_OUTPUT environment variable.

Author: xdelaruelle

tcl/init.tcl.in

@@ -93,6 +93,7 @@ array set g_config_defs [list\
       0 {0 365} {} {} intbe}\
    pager {MODULES_PAGER {@pagercmd@} 0}\
    rcfile {MODULERCFILE <undef> 0}\
+   redirect_output {MODULES_REDIRECT_OUTPUT 1 0 {0 1}}\
    quarantine_support {MODULES_QUARANTINE_SUPPORT @quarantinesupport@ 0 {0\
       1}}\
    run_quarantine {MODULES_RUN_QUARANTINE <undef> 0}\