Added 'pointer_stack_get_slots' procedure to I/O group

The procedure returns the number of free slots in a PointerStack
Corrected allocation logic in push

'Full' respect to limits and locked status
Added truncate on limit existing data

Modified: src/pointer-stack-limitation.c
Rolled back default buffer by 1

Buffer is only incorporated by push which adds one element by default, therefore a value of 8 allocates a 'misaligned block length' users are not restricted to this logic, but the design of modern processors says it would always be optimal to buffer by 1 less than a power of 2 for as long as push adds 1 element by default.
Added missing pointer deref

Modified: src/pointer-stack-limitation.c
Added I/O import pseudo code

Modified: src/include/pointer-stack.h
Modified: src/pointer-stack-io.c
Added a devnote to import

Also added extern def for push