We always require gnuradio-core.
Set lower limit on AM and FM filter width to 500 kHz. Prevents application freeze.
Try to organize include files alphabetically.
Merge remote-tracking branch 'csete/master'
Introduce some input/output pasrameter checks.

When setting device strings or sample rate, check if the new settings
asre different from the old ones and do nothing if the settings haven't
changed. The reduces the number of 'i/o device errors' since we don't
try to re-open the same device.
Suspend DSP during reconfiguration.
Merge remote-tracking branch 'csete/master'
Enable automatic tuner gain by default.
Update suggested sample rates for rtlsdr devices.
Merge remote-tracking branch 'csete/master'