Improve .0

[TG9541]

This is a very minor issue - but anyway.

While testing pictured number output I noticed that .0, signed number output for 3 digit (LED) displays has a few edge cases that don't work: numbers smaller than -994 or larger than 9994 will result in digit overruns - and thus potentially wrong readings.

The updated version tests for a range:

-999 .0 DEF. ok
-995  .0 -99 ok
-99  .0 -9.9 ok
0    .0 0.0 ok
999  .0 99.9 ok
1000 .0 100 ok
7876 .0 788 ok
9995 .0 DEF. ok