Several old bugs squashed.
On the APRS side, most notably, SSID numbers where shifted left twice, instead of once, and bits 5,6 where not properly set.
On AX.25 side, the bit stuffing part of the encoder was not placing the zero bit on the right place.
Finally, I changed APRS icon from ORANGE to GREEN, since even this may be a simple app, now it's doing its work as intended.
Values where left bit-shifted upon being entered by the user, so resulting SSID being transmitted was a different number. This shifting was happening both on Source and Destination SSID values.
Re-enabled the tone key selector in Soundboard
Soundboard now uses OutputStream, like Replay
Constexpr'd a bunch of consts which were going to BSS section
Exiting an app now goes back to main menu
Cleaned up Message array
Made AFSK code more generic (not tied to LCR)
Added modem presets and more options in AFSK setup
String-ized and simplified LCR UI code
Simplified AFSK baseband code, made to always work on 16bit words
