[bugfix] [vector] reserve didn't remember it reserved

Signed-off-by: Shahbaz Youssefi <ShabbyX@gmail.com>
[update] [vector] use sh_vector_at for cleanliness

Signed-off-by: Shahbaz Youssefi <ShabbyX@gmail.com>
[feature] assign-compatible function for structures

Signed-off-by: Shahbaz Youssefi <ShabbyX@gmail.com>
[update] [vector] clean up memory allocation & access

Signed-off-by: Shahbaz Youssefi <ShabbyX@gmail.com>