* Introduce sbBYTES_TO_STORE_MESSAGE_LENGTH
* Fix bug in ucStreamBufferGetStreamBufferType() - which is only used by the
Percepio trace tool.
* Update the line within vTaskStartScheduler() that was setting xTickCount to 0
to instead set it to configINITIAL_TICK_COUNT.
* Introduce xMessageBufferNextLengthBytes() and tests for the same.
* Add call to traceTASK_SWITCHED_IN() in vTaskStartScheduler() so trace tools
can see the first task to run.
* Correct definition of StaticTask_t in the case that portUSE_MPU_WRAPPERS is
set to 1.
* prvTaskCheckFreeStackSpace() now returns configSTACK_DEPTH_TYPE to allow
return values greater than max uint16_t value if required.
* xStreamBufferSend() and xStreamBufferReceive() no longer clear task
notification bits - clearing was unnecessary as only the task notification
state is used.
* Correct out of date comment in tasks.c.
* Fix typo in comment in queue.h.
