fixing hfx.py for proper uhd support - tuning was negative of desired change, removed  antenna tuner support
update README
Fixed other issues with app - changes to fft display - still missing 'tune on click'
fixed click to tune, click mouse on fft display will tune to that frequency
Merge remote-tracking branch 'cswiger/master' into hfx
filter: added a ccc version of the pfb_arb_resampler block.
uhd: hf_explorer example: Added some more options for better handling of rates.

Uses aribtrary resampler to convert from input rate to the requested audio rate.
qtgui: forces min/max sliders for qt_sink waterfall plots to be horizontal.
Merge branch 'maint'
qtgui: in sink_c and sink_f, use volk_malloc/volk_free instead of new for buffers.
filter: fixed use of volk_malloc in fft_filter kernel.