Add clearAll parameter to deinit() (#22)

* Add clearAll parameter to deinit()

Adds the ability to clear all resources consumed during BLE operation when deinitializing and shutting down BLE.
Useful when BLE is used intermittently or in a task that initializes, performs operations then deinitializes.

By setting the clearAll parameter to true all created BLE objects will be deleted, freeing the memory for other tasks.

Warning: This will invalidate any pointers that may be referencing the deleted objects.

* Add bool deleteCallbacks parameter to NimBLEServer::setCallbacks, if true (default) will delete the callback class when server is destructed.

* Delete scan results when scan is destructed.

src/NimBLEDevice.h

@@ -91,7 +91,7 @@ extern "C" void ble_store_config_init(void);
 class NimBLEDevice {
 public:
     static void             init(const std::string &deviceName);
-    static void             deinit();
+    static void             deinit(bool clearAll = false);
     static bool             getInitialized();
     static NimBLEAddress    getAddress();
     static std::string      toString();