New file which contains the migration notes.

MIGRATION

@@ -0,0 +1,47 @@
+===================================
+Migration notes from the 1.2 series
+===================================
+
+Init
+====
+
+modbus_init_tcp requires a third new argument, the port number.
+
+modbus_init_tcp(modbus_param_t *mb_param, char *ip_address, int port)
+
+Set the port to MODBUS_TCP_DEFAULT_PORT to use the default one
+(502). It's convenient to use a port number greater than or equal to
+1024 because it's not necessary to be root to use this port number.
+
+
+Pointers of data
+================
+
+The coil and input status are now stored in an array of type uint8_t
+(in 1.2.X series, array of type int was used).  So now, you need to
+pass a pointer of type uint8_t to use read_coil_status(), for example.
+
+The holding and input registers are now stored in an array of type
+uint16_t.
+
+These changes reduce the memory consumption.
+
+
+New functions
+=============
+
+report_slave_id
+
+modbus_set_error_handling
+modbus_mapping_new
+modbus_mapping_free
+modbus_init_listen_tcp
+modbus_listen
+modbus_manage_query
+
+get_slave_query_tcp
+set_bits_from_byte
+set_bits_from_bytes
+get_byte_from_bits
+
+Read modbus.h for more informations.