Managing ownership in VectorSchemaRoot#addVector, recent changes miss the main fault.

A recent change in VectorSchemaRoot#addVector provided a simple improvement, but completely misses a major shortcoming of this routine and, almost certainly, others like it. Based on the interest in that issue (#301), this issue might be of interest to @axreldable and @jbonofre.

One cannot change the `FieldVector`s belonging to `VectorSchemaRoot`s by simply rearranging the elements of their `List`s without considering the ownership of their underlying buffers. This can cause various problems, particularly when `VectorSchemaRoot`s are closed. This is why `TransferPair` exists.

I would probably need some help with improving this as I'm quite new to using Apache Arrow (and very new to using GitHub). But I have written a possibly improved implementation if this would be of interest and would be open to collaborating on rectifying this bug.

Inizia con VectorSchemaRoot#addVector e leggi la discussione correlata nell’issue #301. Analizza in che modo il riordinamento dei FieldVectors influisce sulla proprietà dei buffer sottostanti e come si comportano i VectorSchemaRoots quando vengono chiusi. Il lavoro è completato quando il trasferimento della proprietà viene gestito correttamente e la chiusura dei roots non causa più i problemi relativi ai buffer descritti.

Scritto dal modello di indicizzazione a partire dal testo della issue.