digital: Python functions to support soft decision making and look-up table generation.
digital: Added a new constellation_soft_decoder block that produces soft decisions as floats instead of hard decisions.

Added documentation for how to use the new soft decision tools.
digital: added a constellation modulator that uses a constellation object to modulate samples.

The constellation object knows the constellation and symbol mappings for any constellation, not just PSK or QAM.
Merge branch 'master' into next
blocks: fixed simple documentation for blocks module (copy/paste error from gr-digital).
docs: Adding documentation for how to use the thread priority API of GR blocks.
Merge branch 'maint'
runtime: fixed bug where average Performance Counters were not being exported into Python.
runtime: exporting msg_edge_list now, too.
Merge branch 'maint'
runtime: exporing high_res_timer functions into Python (can be replaced by native Python calls with Python 3.3).
runtime: Added a Performance Counter that stores the accumulated work_time counter (work_time_total).
cmake: Fixed FindGnuradio.cmake file for new 3.7 locations of headers.

This file should actually be removed since it duplicates the functionality of the cmake-recommended GnuradioConfig.cmake file.
cmake: Fix and cleanup for new Ice library names in OSX through macports.
Merge branch 'maint'
Merge branch 'master' into next
uhd: add top-level exception reporting to uhd_fft
Fix missing module imports in error case
filter: fix rational resampler tap defaults in GRC
modtool: fix GRC XML file creation when no args

Fixes bug where no args produces ($) in make clause