+ Support tickless idle when configUSE_PREEMPTION is 0 (previously tickless idle was only supported when the pre-emptive scheduler was being used).
+ If a stack was statically allocated, then don't try freeing it if the TCB cannot be allocated.
+ Remove use of INCLUDE_xEventGroupsSetBitsFromISR() pre-processor macro, as it was not tested anyway.
Demo app changes:
+ Updated SAM4L Atmel Studio project to use Atmel Studio 7.