Fixed possible race condition in short-lived synchrynous commands

src/main/java/me/legrange/mikrotik/ApiConnection.java

@@ -429,9 +429,11 @@ public class ApiConnection {
 
         private List<Result> getResults() throws ApiCommandException, ApiConnectionException {
             try {
-                synchronized (this) {
+                synchronized (this) { // don't wait if we already have a result. 
+                    if ((err == null) && results.isEmpty()) {
                         wait();
                     }
+                }
             } catch (InterruptedException ex) {
                 throw new ApiConnectionException(ex.getMessage(), ex);
             }