Changes to core code and port layer:

+ Add configASSERT() into ARM Cortex-M ports to check the number of priority
      bit settings.
    + Clear the 'control' register before starting ARM Cortex-M4F ports in case
      the FPU is used before the scheduler is started.  This just saves a few
      bytes on the main stack as it prevents space being left for a later save
      of FPU registers.
    + Added xSemaphoreGetMutexHolderFromISR().
    + Corrected use of portNVIC_PENDSVSET to portNVIC_PENDSVSET_BIT in MPU ports.

FreeRTOS/Source/portable/MemMang/heap_1.c

@@ -104,6 +104,7 @@ task.h is included from an application file. */
 	static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
 #endif /* configAPPLICATION_ALLOCATED_HEAP */
 
+/* Index into the ucHeap array. */
 static size_t xNextFreeByte = ( size_t ) 0;
 
 /*-----------------------------------------------------------*/