Added deps to Ln

public/biopet-framework/src/main/scala/nl/lumc/sasc/biopet/extensions/Ln.scala

@@ -30,6 +30,9 @@ class Ln(val root: Configurable) extends InProcessFunction with Configurable {
   @Output(doc = "Link destination")
   var out: File = _
 
+  @Output
+  var deps: List[File] = Nil
+
   var relative: Boolean = true
 
   lazy val cmd: String = {