More Spectrum changes
- Frequency zooming. Implements #773. Use the mouse wheel inside spectrum or waterfall area.
- Power and time zooming. Implements #779. Use the mouse wheel inside spectrum (power) scale or waterfall (time) scale.
Check documentation here: https://github.com/f4exb/sdrangel/tree/master/sdrgui#mouse-scroll-wheel
Other changes and fixes
- DeviceUISet: fixed channel instance registrations element deletion. Fixes #776
- FileSink: fixed spectrum GUI center frequency setting (baseband to GUI communication)
- FileSink: give .sdriq extension to provided file name automatically. Fixes #780
- SigMFFileSink: give .sigmf-meta extension to provided file name automatically.
- SigMFFileSink: append data if file exists and has been recorded with SDRangel. Implements #781