Fixes #2009: Timer Voice minute call not working for persistent timers

Timers moved to timer.cpp
Added timer overflow protection
Added timer gtests
THt mode now triggers on THR>10%

radio/src/gui/Taranis/view_main.cpp

@@ -35,6 +35,7 @@
  */
 
 #include "../../opentx.h"
+#include "../../timers.h"
 
 #define BIGSIZE       MIDSIZE
 #define LBOX_CENTERX  (BOX_WIDTH/2 + 17)