Add internal reference create and rename functions which take a force
parameter, telling them to overwrite an existing reference if it
exists.
These functions try to update the reference if it's of the same type
as the one it's going to be replaced by. Otherwise the old reference
becomes invalid.
Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
List all the references in the repository, calling a custom
callback for each one.
The listed references may be filtered by type, or using
a bitwise OR of several types. Use the magic value
`GIT_REF_LISTALL` to obtain all references, including
packed ones.
The `callback` function will be called for each of the references
in the repository, and will receive the name of the reference and
the `payload` value passed to this method.
