Sync FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP with the version in GitHub at (23665258cabe49d5d68ba23968b6845a7c80eb34).

Notes: 
- header has version 2.2.0. 
- This sync did not bring in ./test directory, though we should. 
- New NetworkInterfaces are introduced by this merge.
- Keil compiler support. 
- FreeRTOS_IP.h new API xApplicationGetRandomNumber().
- FreeRTOS_IP_Private.h new eIPEvent_t eNetworkTxEvent. 
- FreeRTOS_Stream_Buffer.h removing static xStreamBufferIsEmpty() and xStreamBufferIsFull().
- FreeRTOSConfigDefaults.h provides default ipconfigDNS_RECEIVE_BLOCK_TIME_TICKS. 
- other type changes.

FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/portable/NetworkInterface/ATSAM4E/gmac.c

@@ -429,7 +429,6 @@ void gmac_dev_init(Gmac* p_gmac, gmac_device_t* p_gmac_dev,
 	 * GMAC_DCFGR_TXCOEN: (GMAC_DCFGR) Transmitter Checksum Generation Offload Enable.
 	 * Note: tha SAM4E does have RX checksum offloading
 	 * but TX checksum offloading has NOT been implemented.
-	 * http://community.atmel.com/forum/sam4e-gmac-transmit-checksum-offload-enablesolved
 	 */
 
 	gmac_set_dma(p_gmac,
@@ -658,7 +657,7 @@ uint32_t gmac_dev_write(gmac_device_t* p_gmac_dev, void *p_buffer,
 		}
 		#else
 		{
-			/* Or memcopy... */
+			/* Or Memcopy... */
 			memcpy((void *)p_tx_td->addr, p_buffer, ul_size);
 		}
 		#endif /* ipconfigZERO_COPY_TX_DRIVER */