[Mina 3][Wishlist] remove IoBuffer#getObject()

[Christian Schwarz]

Somewere i read that the class IoBuffer will not be used in Mina 3
anymore, if not the methods IoBuffer#getObject() /IoBuffer#putObject()
should be removed ! I think it's better to use a dedicated
SerialisationDe-/Encoder. It is difficult to imagine what exactly
happens when you have no serialization encoder in the filter chain an
write Object to the IoBuffer.