Extended_encoder ignores get_output_conversion()

Hey list,

‘extended_encoder’ currently ignores whatever ‘get_output_conversion’
returns. If you use FEC’s extended encoder and you reimplement
‘get_output_conversion’, it gets ignored. A quick look at the
available encoders in gr-fec shows, that none of them actually uses
that method. Though the docs state that
* If ‘packed_bits’, the block produces packed bits and the
* wrapper should unpack these (using, for instance,
* gr::block::unpack_k_bits_bb(8)).

Thus I created a little patch which would fix that.
Also I just sent a pull request for that.