Various RTOS classes were storing their CMSIS-RTOS creation attribute
structure as a member, when it's not required after construction. Reduce
memory by eliminating this member.
Provide fix for pool buffer size: pool block size must be
a multiple of 4 bytes.
Add assertion to forbid creation of MemoryPool object with queue size equal to 0.
Update description of free() function. Add information about
statuses returned by this function.