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/machine/machine_table.c

@@ -25,12 +25,12 @@
 #include <stdint.h>
 #include <string.h>
 #include <wchar.h>
-#include "86box.h"
+#include <86box/86box.h>
 #include "cpu.h"
-#include "mem.h"
-#include "rom.h"
-#include "device.h"
-#include "machine.h"
+#include <86box/mem.h>
+#include <86box/rom.h>
+#include <86box/device.h>
+#include <86box/machine.h>
 
 
 #ifdef USE_NEW_DYNAREC