Remove duplicated ArduinoCore-API files (#840)

Use #include .... to reference them from the cores directory to ensure
they keep up to date.

Author: earlephilhower

ArduinoCore-API

@@ -1,57 +1,2 @@
-/*
-  Arduino API main include
-  Copyright (c) 2016 Arduino LLC. All right reserved.
-
-  This library is free software; you can redistribute it and/or
-  modify it under the terms of the GNU Lesser General Public
-  License as published by the Free Software Foundation; either
-  version 2.1 of the License, or (at your option) any later version.
-
-  This library is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public
-  License along with this library; if not, write to the Free Software
-  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-*/
-
-#ifndef ARDUINO_API_H
-#define ARDUINO_API_H
-
-// version 1.2.0
-#define ARDUINO_API_VERSION 10200
-
-#include "Binary.h"
-
-#ifdef __cplusplus
-#include "Interrupts.h"
-#include "IPAddress.h"
-#include "Print.h"
-#include "Printable.h"
-#include "PluggableUSB.h"
-#include "Server.h"
-#include "String.h"
-#include "Stream.h"
-#include "Udp.h"
-#include "USBAPI.h"
-#include "WCharacter.h"
-#endif
-
-/* Standard C library includes */
-#include <stdlib.h>
-#include <stdint.h>
-#include <stdbool.h>
-#include <string.h>
-#include <math.h>
-
-// Misc Arduino core functions
-#include "Common.h"
-
-#ifdef __cplusplus
-// Compatibility layer for older code
-#include "Compat.h"
-#endif
-
-#endif
+#pragma once
+#include "../../../ArduinoCore-API/api/ArduinoAPI.h"