Added basic driver example use code to the library documentation.

Made the USARTStream global public and documented in the SerialStream module, allowing for the serial USART stream to be accessed via its handle rather than via the implicit stdout and stdin streams.

LUFA/Drivers/Peripheral/AVRU4U6U7/ADC.h

@@ -47,6 +47,24 @@
  *  \note This file should not be included directly. It is automatically included as needed by the ADC driver
  *        dispatch header located in LUFA/Drivers/Peripheral/ADC.h.
  *
+ *  <b>Example Usage:</b>
+ *  \code
+ *      // Initialise the ADC driver before first use
+ *      ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
+ *
+ *      // Must setup the ADC channel to read beforehand
+ *      ADC_SetupChannel(1);
+ *
+ *      // Perform a single conversion of the ADC channel 1
+ *      ADC_GetChannelReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | ADC_CHANNEL1);
+ *      printf("Conversion Result: %d\r\n", ADC_GetResult());
+ *
+ *      // Start reading ADC channel 1 in free running (continuous conversion) mode
+ *      ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | ADC_CHANNEL1);
+ *      while (!(ADC_IsReadingComplete())) {};
+ *      printf("Conversion Result: %d\r\n", ADC_GetResult());
+ *  \endcode
+ *
  *  @{
  */