Implement 'segment_array' that allocates memory using ba_alloc

[bratpiorka]

Rationale

It is needed whenever we want to allocate an array (e.g. in memspaces) using ba_alloc with a fixed-sized pool.

API Changes

The API could be something like this:

#define SEGMENT_DECLARE(type, num_elems) struct segment_#type#_#num_elems#_t { \
type elems[num_elems]; \
struct segment_t *next; \
};

#define SEGMENT(type, size) (struct segment_#type#_#num_elems#_t)

void segment_array_create(ba_alloc alloc, size_t segmentSize, size_t numSegments);

#define SEGMENT_CREATE(alloc, type, num_elements) ((SEGMENT(type, num_elements)*) segment_array_create(alloc, sizeof(type) * num_elements + 8, 1));

void segmentArrayDestroy(ba_alloc* alloc);

[bratpiorka]

@igchor this has been moved from JIRA to Github because of the JIRA cleanup. Can you add more information on why we might need this feature?