Consider including hsndfile-vector in hsndfile package

[kaoskorobase]

Consider including the Buffer instances from hsndfile-vector directly in the hsndfile package. The vector package is now quite ubiquitous and depending on it shouldn't hurt.

See also #15.

[TristanCacqueray]

Hello @kaoskorobase , thank you for hsndfile, I started using it and proposed a few improvements, hope that's ok for you.