adds nvs erase

// #define WM_ERASE_NVS // esp32 erase() will erase NVS

WiFiManager.cpp

@@ -1545,6 +1545,17 @@ void WiFiManager::reboot(){
  */
 bool WiFiManager::erase(){
   DEBUG_WM("Erasing");
+
+  #if defined(WM_ERASE_NVS)
+    DEBUG_WM("Erasing NVS");
+    int err;
+    err=nvs_flash_init();
+    DEBUG_WM("nvs_flash_init: ",err ? err : "Success");
+    err=nvs_flash_erase();
+    DEBUG_WM("nvs_flash_erase: ", ? err : "Success");
+    return;
+  #endif
+      
   return WiFi_eraseConfig();
 }
 
@@ -2119,4 +2130,4 @@ void WiFiManager::WiFi_autoReconnect(){
       WiFi.onEvent(WiFiEvent);
     }  
   #endif
-}
+}

WiFiManager.h

@@ -16,6 +16,7 @@
 #define WM_WEBSERVERSHIM // use webserver shim lib
 // #define WM_MDNS       // use MDNS
 // #define WM_FIXERASECONFIG // use erase flash fix
+// #define WM_ERASE_NVS // esp32 erase() will erase NVS
 
 #ifdef ESP8266
 
@@ -51,6 +52,11 @@
         #endif
     #endif
 
+    #ifdef WM_ERASE_NVS
+       #include <nvs.h>
+       #include <nvs_flash.h>
+    #endif
+
     #ifdef WM_MDNS
         #include <ESPmDNS.h>
     #endif