Merge branch 'sync' of git@gnuradio.org:trondeau into master

Merge branch 'sync' of git@gnuradio.org:trondeau into master

This merge adds polyphase clock recovery, implements new PAM demodulators
that use it, and also moves GRC examples to gnuradio-examples component.

See merge commit diff for updated files post merge.

* 'sync' of git@gnuradio.org:trondeau: (54 commits)
  Reverting dqpsk to be mpsk_receiver based and not change its behavior.
  Fixing initialization of timing gains. Alpha should be < 1, and beta should be << 1.
  This splits the rate into a fractional an integer value, which allows the loop to adjust the fractional rate while the integer rate keeps the increments moving properly. Allows the max rate deviation to be independent of the integer rate. Scaling of the differential taps also allows alpha and beta to operate independent of the rate when fractional samples per symbol are used. Slightly more tolerant to large signal values, but they still should be close to +/-1.
  Fixing compiler warnings.
  Adding dqpsk2 block to makefile for installation.
  Adding DQPSK version that uses the PFB timing sync block (dqpsk2).
  Minor fixes for logging.
  Fixing import of UI file.
  Temporary working dbpsk2 example until we match everything.
  Working DBPSK implementation with new PFB clock recovery block. The feedforward AGC wasn't playing nicely, the frequency aquistion range was increased to swing half the sample rate in either direction, and the number of filter phases to use was increased to 32.
  A bit of code cleanup.
  Starting to rework QT app to control new PFB clock recovery alg.
  Making old dbpsk work again to compare against new version.
  Adding new DBPSK block with new PFB clock recovery alg.
  Revert "More additions to PAM timing simulation."
  More additions to PAM timing simulation.
  Using 2-PAM by default.
  Cleaning up GRC PAM timing example and adding ability to do M-ary PAM.
  Cleaning up constructor.
  Moving filter number decision to start work function.
  ...