digital: bugfixes to ofdm_chanest, HPD and frame EQ
digital: crude hack to prevent the HPD from crashing flow graphs
blocks: fix for ~file_source crash, Bug #550
audio: switch default also device from hw:0,0 to default, Bug #551

Conflicts:

	gr-audio/lib/alsa/alsa_sink.cc
	gr-audio/lib/alsa/alsa_source.cc
Revert "wxgui: Fixes to solve issues using GL sinks on OS X"

This reverts commit 5f0aaf3d5397675d6f87acd7ab20526ac1fb0d4e.

Issues reported with blank displays on some non-OSX systems.
Merge remote-tracking branch 'martin/maint-ofdm' into maint