allow user loop while in AP mode

WiFiManager.cpp

@@ -252,6 +252,10 @@ boolean  WiFiManager::startConfigPortal(char const *apName, char const *apPasswo
         break;
       }
     }
+
+    if (_loop)
+      _loop();
+
     yield();
   }
 

WiFiManager.h

@@ -118,6 +118,8 @@ class WiFiManager
     //if this is true, remove duplicated Access Points - defaut true
     void          setRemoveDuplicateAPs(boolean removeDuplicates);
 
+    void          setUserLoopInAP (void (*loop)()) { _loop = loop; }
+
   private:
     std::unique_ptr<DNSServer>        dnsServer;
     std::unique_ptr<ESP8266WebServer> server;
@@ -137,6 +139,7 @@ class WiFiManager
     unsigned long _configPortalTimeout    = 0;
     unsigned long _connectTimeout         = 0;
     unsigned long _configPortalStart      = 0;
+    void          (*_loop)()              = 0;
 
     IPAddress     _ap_static_ip;
     IPAddress     _ap_static_gw;