- Add early NULL check to ta_free()
- Add overflow checks in alloc_block() and ta_calloc()
- Clear full block size to 0's in ta_calloc()
- Optionally set errno to ENOMEM when out of memory
- Optionally use memset() to implement memclear()
- Add ta_getsize() to return allocated block size
- Add ta_realloc() (optional, requires memcpy())
ta_getsize() and ta_realloc() are based on ideas from thi-ng#11, but rewritten
to fix various issues in that PR.