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.
runtime: fixed bug where average Performance Counters were not being exported into Python.
runtime: exporting msg_edge_list now, too.
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.