Maintenance release
- ADS-B demod: optimization of sync word correlation. Implements #675
- ADS-B: added 2MS/s sample rate
- Fix and refactor FIR filter (from kasper93)
- NFMDemodSink: Fixes and minor refactoring (from kasper93). Issue #674
- NFM: augmented CTCSS tones. Implements #664
- CTCSS detector: fixed crash on destructor. Fixes #680
- TestSource: fixed timer start/stop. Fixes issue #661
- Main Window: fixed sampling device changed. Fixes #668
- Scope MagSq trigger fix. Fixes #669