OP25j

= Refactoring OP25 =

• The cmake build splits the classes for a block into an impl/interface and has new namespace rules that we should comply with.
  This is pretty straightforward and documented [[http://gnuradio.org/redmine/projects/gnuradio/wiki/BlocksCodingGuide here]].
• Expose more of our components at a lower level because we can use GNURadio to schedule execution across multiple threads/CPUs.
  We already have some of the C4FM demod/mod, DQPSK demod/mod, vocoder and so on but we need to expose the bit correlator, packetizer (decoder) and so on.