[Gzz] ``vob_interface--benja``: Make ``Vob`` an interface

[Benja Fallenstein]

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``vob_interface--benja``: Make ``Vob`` an interface
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:Author:   Benja Fallenstein
:Date:     2003-02-23
:Type:     Interface
:Scope:    Minor
:Status:   Current


``Vob`` is currently an abstract class; for Java,
central things like this are usually interfaces,
allowing for multiple inheritance, e.g.
subinterfaces ``ColorableVob`` and ``ShapableVob``
or something like that, both of which could be
implemented by the same class.

To conform better to the usual conventions,
make ``Vob`` an interface and provide
an abstract implementation (``AbstractVob``).

\- Benja