KiwiSDR TDoA extension

KiwiSDR v1.196 includes a KiwiSDR extension (based on https://github.com/hcab14/TDoA)

Note that ionospheric delays are not taken into account, so depending on the geometry of receivers and the target the TDoA maps will be biased.

Many thanks to John Seamons, ZL/KF6VO.

In parallel I am working on a real-time version of TDoA using python/matplotlib/cartopy.