mkexp: make cdexp shell function robust against dir variables containing _DIR

mkexp.bash

@@ -35,6 +35,8 @@ cdexp () {
         echo 'Oops: invalid number of parameters' >&2
         return 1
     fi
-    vardir=$(getexp -p "$dir" -k "${var^^}_DIR" "$cfg") &&
+    var=${var^^};
+    var=${var%_DIR};
+    vardir=$(builtin cd "$dir" && getexp -k "${var}_DIR" "$cfg") &&
         cd "$vardir"
 }