Merge pull request #1 from csete/master

merging fork
Merge pull request #2 from csete/master

pull
Add support for Airspy sample rates.

Patch received from Dimitri Stolnikov.
Update callsign for Göran Weinholt.
Add command line option to list existing configurations.
Add .desktop file for better linux user expirence
Set Icon value

Set icon value since gqrx.svg is to be installed by deb package.
Fix typo
Add new I/Q recorder and player (WIP).
Merge pull request #152 from oxapentane/master

Add .desktop file for better linux user expirence
Fix .desktop file according to freedesktop spec
Merge pull request #154 from oxapentane/fix-desktop-file

Fix .desktop file according to freedesktop spec
Only connect I/Q sink if we are recording.
Improve audio recorder robustness.

This patch improives the robustness while recording audio and
performing various operations, such as switching demodualtors
off.
Use shorter I/Q file names.
Functional I/Q recorder.
New I/Q player (WIP)
Restore manual gain settings when HW AGC is diabled.

Fixes one part of issue #141.
Note that gqrx does actually restore AGC, but for some reason the
device ends up having a wrong gain setting.
Fix invalid rtlsdr sample rate selection in I/O config.
Connect new remote freq signal to CFreqCtrl.

This fixes an issue where the frequency controller display didn't
update on certain remote frequency requests.