Use "$PWD" as source by default

src/libexec/saturnin-ln

 "
 
 usage() {
-    usage_is "[-f|--force] [-t|--target TARGET] SOURCE [NAME]"
+    usage_is "[-f|--force] [-t|--target TARGET] [SOURCE] [NAME]"
 }
 
 link() {
     -t|--target)        target=$2           shift 2 ;;
     --help)             usage                       ;;
     -*)                 usage                       ;;
-    "")                 usage                       ;;
     *)                  src=$1; name=$2;    break   ;;
 esac done
 
 test -z "$target"               && target=$(load target)
 test -z "$target"               && target=$DEFAULT_TARGET
 test -z "$name"                 && name="$(basename "$PWD")"
+test -z "$src"                  && src="."
 
 debug -v name target