Import lwIP contrib rep

... from http://git.savannah.gnu.org/cgit/lwip/lwip-contrib.git/ into contrib/ subdir, STABLE-2_1_0_RELEASE tag
lwIP contrib is now officially frozen
TODO: Fix build

contrib/ports/unix/port/include/netif/sio.h

@@ -0,0 +1,60 @@
+#ifndef SIO_UNIX_H
+#define SIO_UNIX_H
+
+#include "lwip/sys.h"
+#include "lwip/netif.h"
+#include "netif/fifo.h"
+/*#include "netif/pppif.h"*/
+
+struct sio_status_s {
+	int fd;
+	fifo_t myfifo;
+};
+
+/* BAUDRATE is defined in sio.c as it is implementation specific */
+/** Baudrates */
+typedef enum sioBaudrates {
+	SIO_BAUD_9600,
+	SIO_BAUD_19200,
+	SIO_BAUD_38400,
+	SIO_BAUD_57600,	
+	SIO_BAUD_115200	
+} sioBaudrates;
+
+/**
+* Poll for a new character from incoming data stream
+* @param 	siostat siostatus struct, contains sio instance data, given by sio_open
+* @return 	char read from input stream, or < 0 if no char was available
+*/
+s16_t sio_poll(sio_status_t * siostat);
+
+/**
+*	Parse incoming characters until a string str is recieved, blocking call
+* @param	str		zero terminated string to expect
+* @param 	siostat siostatus struct, contains sio instance data, given by sio_open
+*/
+void sio_expect_string(u8_t *str, sio_status_t * siostat);
+
+/**
+* Write a char to output data stream
+* @param 	str		pointer to a zero terminated string
+* @param	siostat siostatus struct, contains sio instance data, given by sio_open
+*/
+void sio_send_string(u8_t *str, sio_status_t * siostat);
+
+/**
+*	Flush outbuffer (send everything in buffer now), useful if some layer below is 
+*	holding on to data, waitng to fill a buffer
+* @param 	siostat siostatus struct, contains sio instance data, given by sio_open
+*/
+void sio_flush( sio_status_t * siostat );
+
+/**
+*	Change baudrate of port, may close and reopen port
+* @param 	baud	new baudrate
+* @param 	siostat siostatus struct, contains sio instance data, given by sio_open
+*/
+void sio_change_baud( sioBaudrates baud, sio_status_t * siostat );
+
+#endif
+