cleanup main program initialization and add stdtime function to libs

lib/filefct.sh

@@ -1,4 +1,11 @@
 
+# Define normalised time display, filename friendly
+stdtime()
+{
+    date --rfc-3339=seconds | sed -e 's/ /-/' -e 's/://g'
+}
+export -f stdtime
+
 # Backup original installation files
 # (or any old files if runned several time on same file)
 backupdist()
@@ -9,7 +16,7 @@ backupdist()
 
     for file in $@; do
 	if [[ -e ${file} ]]; then
-	    tmpstmp=$(date --rfc-3339=seconds | sed -e 's/ /-/' -e 's/://g')
+	    tmpstmp=$(stdtime)
 	    prnt I "Création d'une sauvegarde de ${file} du $tmpstmp..."
 	    cp -av $file $file.dist.$tmpstmp
      	fi