gr: added GR_TEST_ENVIRONS to GrTest
Removing gruel from QA python paths.
channels: new frequency selective fading block
Merge remote-tracking branch 'osh/master'
Merge remote-tracking branch 'jblum/gr_test_extra_environs'
channels: selective fading model cleanup
runtime: fix for timer issue that was causing qtgui components to not plot
Merge remote-tracking branch 'osh/master'
blocks: fix use of assertGreater in QA for older Python
Merge branch 'maint'

Conflicts:
	gr-blocks/python/blocks/qa_file_metadata.py
runtime: Move logic from block.h to block.cc.
docs: Removing gr-shd from sphinx docs.
Merge remote-tracking branch 'reynwar/minorfixes'
blocks: plateau_detector_fb is now a gr_block and forecasts

The detector actually could return 0 with insufficient input.
The forecast always requires at least 2*d_max_len.
However, forecast could be conditionalized to only
require this based on the last threshold detected.