* Allow apps to not use persisted freq.
* use rx_freq for RX mode
* remove direct call to persistant_memory in tx_model
* app_setting defaults, and tx_view to use ctor value
* ui_transmitter : Added rf_amp field
* ui_transmitter : Added color grading depending on gain settings
* Removed TransmitterModel::set_rf_amp(bool) call from every apps loading ui_transmit
* transmitter_model : RF_amp disabled by default
* APRS Tx app : Fixed frequency keypad not showing up
* Morse Tx app : Removed TransmitterModel::set_lna() and TransmitterModel::set_vga() calls