AP_Math: correct copyright, add pragma-once

libraries/AP_Math/crc.h

@@ -15,6 +15,7 @@
 /*
   interfaces to ArduPilot collection of CRCs. 
  */
+#pragma once
 
 uint8_t crc_crc8(const uint8_t *p, uint8_t len);
 uint16_t crc_xmodem_update(uint16_t crc, uint8_t data);

libraries/AP_Math/vector2.h

@@ -24,7 +24,7 @@
 *          18-12-2003
 *          06-06-2004
 *
-* © 2003, This code is provided "as is" and you can use it freely as long as
+* Copyright 2003, This code is provided "as is" and you can use it freely as long as
 * credit is given to Bill Perone in the application it is used in
 ****************************************/
 #pragma once