* add a little Stash utility.
* add radio state RAII helper.
* first part of radio_state changes
* add radio_state_ to rest of apps
* fix freq_step and format
* fix unused ui_sigfrx: corrected sample rate, added back freq setting
I choose what I think are the best Titles based on existing titles/class names and so on. There were also inconsistencies between TX and Transmit and RX and receive. I renamed them to shorter version TX and RX also added it as suffix where possible to make it clearer in what mode you are in. If you have any other title suggestions or changes please use Add comment on Files Changed Screen so I can change it.
Add Gain control to the GPS Sim App .
(we are clonning the two previous PR's n #395 and #446 of the Replay App, correcting TX Gain control to this GPS Sim App )
