add check to dissallow starting cp if already running

This will avoid support inquiries and add a log

WiFiManager.cpp

@@ -657,6 +657,13 @@ boolean WiFiManager::startConfigPortal() {
 boolean  WiFiManager::startConfigPortal(char const *apName, char const *apPassword) {
   _begin();
 
+  if(configPortalActive){
+    #ifdef WM_DEBUG_LEVEL
+    DEBUG_WM(DEBUG_VERBOSE,F("Starting Config Portal FAILED, is already running"));
+    #endif    
+    return false;
+  }
+
   //setup AP
   _apName     = apName; // @todo check valid apname ?
   _apPassword = apPassword;