Add portYIELD_FROM_ISR() macros to Cortex-M ports. The new macro just calls the exiting portEND_SWITCHING_ISR() macro.
Remove code from the MSVC port layer that was left over from a previous implementation and become obsolete.
Update the tickless idle implementations that use up counters for tick interrupt generate to ensure they remain in low power mode for the desired time instead of one tick less than the desired time.
Changed eTaskStateGet() to eTaskGetState() and added #define to ensure backward compatibility.
Added configEXPECTED_IDLE_TIME_BEFORE_SLEEP definition - was previously hard coded to 2.
Slight change to the default CM3 tickless sleep function to allow the idle time to be set to zero in the pre-sleep processing macro.
Changed stack alignment for the FreeRTOS-MPU port to ensure it didn't trigger the assert() in the generic create function.
Replaced the #error that traps configMAX_SYSCALL_INTERRUPT_PRIORITY being set to 0 with a configASSERT() for GCC Cortex-M3/4 ports as the #error does not work if configMAX_SYSCALL_INTERRUPT_PRIORITY includes any casting. Not a problem for other compilers as they cannot have casting anyway as that would break the assembly code.