add dmenufm and modify makefile

dmenufm

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+while true; do
+    choice=`ls -a | dmenu`;
+    [ -d $choice ] && cd $choice;
+    [ -f $choice ] && printf "%s\n" "$choice" && exit 0;
+    [ "$choice" = '!quit' ] && exit 0;
+done
+exit 1;