+avoid retransmitting too often (S9.2 C l114-)
+
+as a result of running, then touching track near panel to induce detection
+
+
layout polarity diagram colourful segment encoding:
- have to fix it so that points' fixed bits are always drawn
+ make moveable feature selection in subseg2display bitwise rather than
+ setwise
-1. Write lots and lots and lots of PIC programs
+safety system no crashes at crossovers please