Merge pull request #1 from csete/master

merging fork
Merge pull request #2 from csete/master

pull
Work on I/Q recorder and player.
Work on I/Q plotter.
Connect file seek signal to gr-osmosdr source.
Merge pull request #3 from csete/master

pull
updated freq step to 6250Hz
snap-to-freq update
updated AM and NBFM click resolution to 6250Hz
updated device string tooltip with uhd lo_offset option
reverted to master version of mainwindow.cpp
Merge pull request #164 from m0mik/tooltip_update_lo_offset

Updated device string tooltip with uhd lo_offset option.
Remove extra line breaks from HTML forrmatted tooltip.
New API for enumerating audio devices on OS X (issue #101).
Switch back to coreaudio backend on OS X.

Since GNU Radio 3.7.3 we can use the Coreaudio backend again.
This commit also fixes issue #101.
Automatically update I/Q file length while recording.
Fix spelling.
Always reset sample rate.

This is necessary when switching from I/Q fil playback to rtlsdr
input device.
Rename scope.svg to gqrx.svg.

Fixes issue #150.
Add gqrx.desktop file to project.