This change makes all non-user-creatable structures non-comparable. This
makes it easier to add changes later that don't introduce breaking
changes from the go compatibility guarantees perspective.
An Object should be about representing a libgit2 object rather than
showing which methods it should support.
Change any return of Object to *Object and provide methods to convert
between this and the particular type.
lhchavez
Suhaib Mujahid
Carlos Martín Nieto
Calin Seciu