Don't deprecate the mode property in twisted.internet.interfaces

New submission from thijs <[email protected]>:

The following interfaces have a {{{mode}}} property that is marked as deprecated but apparently "on many (most) platforms, 'mode' is respected; on the ones where it's not, I think it's a bug.  Plus, it's hard to correctly implement modes yourself (I had to recently, and I got it wrong twice in a row, thanks to mode/mask confusion)".

 - {{{IReactorUNIX.listenUNIX}}}
 - {{{IReactorUNIXDatagram.connectUNIXDatagram}}}
 - {{{IReactorUNIXDatagram.listenUNIXDatagram}}}

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Type     : defect
Component: core
Keywords : 
Priority : normal
Nosy     : thijs
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http://twistedmatrix.com/trac/ticket/4078