Move all include files to src/include

- 86Box's own headers go to /86box
- munt's public interface goes to /mt32emu
- all slirp headers go to /slirp (might want to consider using only its public inteface)
- single file headers from other projects go in include root

src/floppy/fdd_mfm.c

@@ -22,14 +22,14 @@
 #include <string.h>
 #include <wchar.h>
 #define HAVE_STDARG_H
-#include "86box.h"
-#include "timer.h"
-#include "plat.h"
-#include "fdd.h"
-#include "fdd_86f.h"
-#include "fdd_img.h"
-#include "fdd_mfm.h"
-#include "fdc.h"
+#include <86box/86box.h>
+#include <86box/timer.h>
+#include <86box/plat.h>
+#include <86box/fdd.h>
+#include <86box/fdd_86f.h>
+#include <86box/fdd_img.h>
+#include <86box/fdd_mfm.h>
+#include <86box/fdc.h>
 
 
 #pragma pack(push,1)