Changed API, fixed mem leak; Added: seq_read_ alloc/dealloc (stack) + new/free (heap)

Create and destroy a read on the stack

    read_t* seq_read_alloc(read_t*)
    seq_read_dealloc(read_t* r)

e.g.
    read_t r;
    seq_read_alloc(&r);
    ...
    seq_read_dealloc(&r);

Create and destroy a read on the heap

    read_t* seq_read_new()
    seq_read_free(read_t* r)

e.g.
    read_t *r;
    seq_read_new(r);
    ...
    seq_read_free(r);