Added TX Gain control & code simplification

A bug that enabling audio RX resets the TX gain (perhaps because that changing to receiving mode modifies some registers)  inspired me to add this gain control.
Commented out some steps which don't require for the VU meter to work again.
Moved some widgets for gain control.

firmware/application/apps/ui_mictx.cpp

@@ -140,11 +140,13 @@ void MicTXView::rxaudio(bool is_on) {
 		baseband::shutdown();
 		baseband::run_image(portapack::spi_flash::image_tag_mic_tx);
 		audio::input::start();
-		transmitter_model.enable();		
+//		transmitter_model.enable();		
 		portapack::pin_i2s0_rx_sda.mode(3);
-		transmitting = false;
+//		transmitting = false;
 		configure_baseband();
-		transmitter_model.disable();
+//		transmitter_model.disable();
+		transmitter_model.set_tx_gain(transmitter_model.tx_gain());
+		transmitter_model.set_rf_amp(transmitter_model.rf_amp());
 	}
 }
 
@@ -172,6 +174,8 @@ MicTXView::MicTXView(
 		&field_va_attack,
 		&field_va_decay,
 		&field_bw,
+		&field_rfgain,
+		&field_rfamp,
 		&field_frequency,
 		&options_tone_key,
 		&check_rogerbeep,
@@ -213,6 +217,17 @@ MicTXView::MicTXView(
 	};
 	field_bw.set_value(10);
 	
+	field_rfgain.on_change = [this](int32_t v) {
+		transmitter_model.set_tx_gain(v);
+	};
+	field_rfgain.set_value(transmitter_model.tx_gain());
+	
+	field_rfamp.on_change = [this](int32_t v) {
+		transmitter_model.set_rf_amp((bool)v);
+	};
+	field_rfamp.set_value(transmitter_model.rf_amp() ? 14 : 0);
+	
+	
 	check_va.on_select = [this](Checkbox&, bool v) {
 		va_enabled = v;
 		text_ptt.hidden(v);			//hide / show PTT text
@@ -241,7 +256,7 @@ MicTXView::MicTXView(
 	field_va_decay.set_value(1000);
 
 	check_rxactive.on_select = [this](Checkbox&, bool v) {
-		//vumeter.set_value(0);	//Start with a clean vumeter
+//		vumeter.set_value(0);	//Start with a clean vumeter
 		rx_enabled = v;
 		check_va.hidden(v); 	//Hide or show voice activation
 		rxaudio(v);				//Activate-Deactivate audio rx accordingly