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/include/86box/ppi.h

@@ -0,0 +1,18 @@
+#ifndef EMU_PPI_H
+# define EMU_PPI_H
+
+
+typedef struct PPI {
+    int		s2;
+    uint8_t	pa,pb;
+} PPI;
+
+
+extern int	ppispeakon;
+extern PPI	ppi;
+
+
+extern void	ppi_reset(void);
+
+
+#endif	/*EMU_PPI_H*/