fl2k-based signal generator

Utilizing fl2k (FL2000-based USB3-SVGA video adapter) as a bench signal generator with TUI.

To build fl2k_signal_generator you need GNU make, pkg-config, ncurses and osmo-fl2k installed in your system. Just hit make to build it. Then after running ./fl2k_signal_generator you will see something like this:

More info on fl2k abuse: https://osmocom.org/projects/osmo-fl2k/wiki