AP_RCMapper: standardize inclusion of libaries headers

This commit changes the way libraries headers are included in source files:

 - If the header is in the same directory the source belongs to, so the
 notation '#include ""' is used with the path relative to the directory
 containing the source.

 - If the header is outside the directory containing the source, then we use
 the notation '#include <>' with the path relative to libraries folder.

Some of the advantages of such approach:

 - Only one search path for libraries headers.

 - OSs like Windows may have a better lookup time.

libraries/AP_RCMapper/AP_RCMapper.cpp

@@ -1,7 +1,7 @@
 /// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 
-#include <AP_HAL.h>
-#include <AP_RCMapper.h>
+#include <AP_HAL/AP_HAL.h>
+#include "AP_RCMapper.h"
 
 const AP_Param::GroupInfo RCMapper::var_info[] PROGMEM = {
     // @Param: ROLL

libraries/AP_RCMapper/AP_RCMapper.h

@@ -3,8 +3,8 @@
 #define AP_RCMAPPER_H
 
 #include <inttypes.h>
-#include <AP_Common.h>
-#include <AP_Param.h>
+#include <AP_Common/AP_Common.h>
+#include <AP_Param/AP_Param.h>
 
 class RCMapper
 {