[all] Timers countdown / minute beep are configurable

[stock] Port from a part of Andreas patch relative to timers. Thanks Andreas! It allowed me to implement the configurable beeps for timers at a almost 0 flash cost.

src/eeprom_arm.cpp

@@ -409,7 +409,7 @@ void eeLoadModel(uint8_t id)
     memclear(lastFunctionTime, sizeof(lastFunctionTime));
 
     for (uint8_t i=0; i<MAX_TIMERS; i++) {
-      if (g_model.timers[i].remanent) {
+      if (g_model.timers[i].persistent) {
         s_timerVal[i] = g_model.timers[i].value;
       }
     }