delay mine checks to 1 minute intervals

src/engine/workthreads/MineThread.java

@@ -22,18 +22,23 @@ public class MineThread  implements Runnable {
     }
     @Override
     public void run() {
-        //LocalDateTime nextPulse = LocalDateTime.now().withMinute(0).withSecond(0).withNano(0);
+        LocalDateTime nextPulse = LocalDateTime.now().withMinute(0).withSecond(0).withNano(0);
         while (true) {
+
+            LocalDateTime now = LocalDateTime.now();
+            if(now.isBefore(nextPulse))
+                break;
+            nextPulse = nextPulse.plusMinutes(1);
             for (Mine mine : Mine.getMines()) {
 
                 if(mine.wasClaimed)
                     continue;
-                LocalDateTime now = LocalDateTime.now();
+
                 int minute = 0;
                 if (!mine.firstThirty)
                     minute = 30;
 
-                LocalDateTime openTime = LocalDateTime.now().withHour(mine.liveTime).withMinute(minute).withSecond(0);
+                LocalDateTime openTime = now.withHour(mine.liveTime).withMinute(minute).withSecond(0);
                 LocalDateTime closeTime = openTime.plusMinutes(30);
 
                 if (now.isAfter(openTime) && !mine.isActive) {