Merge pull request #160 from KurtE/SerialEvent6

Add serialEvent6 to yield

teensy3/yield.cpp

@@ -49,6 +49,9 @@ void yield(void)
 #endif
 #ifdef HAS_KINETISK_UART4
 	if (Serial5.available()) serialEvent5();
+#endif
+#if defined(HAS_KINETISK_UART5) || defined (HAS_KINETISK_LPUART0)
+	if (Serial6.available()) serialEvent6();
 #endif
 	running = 0;
 };