20 days of unstoppable work. Waiting fo go 1.8, I didn't finish yet, some touches remains.

Former-commit-id: ed84f99c89f43fe5e980a8e6d0ee22c186f0e1b9

adaptors/httprouter/urlpath.go

@@ -0,0 +1,23 @@
+package httprouter
+
+func joinPathArguments(args ...interface{}) []interface{} {
+	arguments := args[0:]
+	for i, v := range arguments {
+		if arr, ok := v.([]string); ok {
+			if len(arr) > 0 {
+				interfaceArr := make([]interface{}, len(arr))
+				for j, sv := range arr {
+					interfaceArr[j] = sv
+				}
+				// replace the current slice
+				// with the first string element (always as interface{})
+				arguments[i] = interfaceArr[0]
+				// append the rest of them to the slice itself
+				// the range is not affected by these things in go,
+				// so we are safe to do it.
+				arguments = append(args, interfaceArr[1:]...)
+			}
+		}
+	}
+	return arguments
+}