Add human-friendly formatting to runtime

src/spectator/formatters/default_formatter.cr

@@ -64,7 +64,25 @@ module Spectator
       end
 
       private def human_time(span : Time::Span)
-        span.to_s
+        millis = span.total_milliseconds
+        return "#{(millis * 1000).round.to_i} microseconds" if millis < 1
+
+        seconds = span.total_seconds
+        return "#{millis.round(2)} milliseconds" if seconds < 1
+        return "#{seconds.round(2)} seconds" if seconds < 60
+
+        int_seconds = seconds.to_i
+        minutes = int_seconds / 60
+        int_seconds %= 60
+        return sprintf("%i:%02i", minutes, int_seconds) if minutes < 60
+
+        hours = minutes / 60
+        minutes %= 60
+        return sprintf("%i:%02i:%02i", hours, minutes, int_seconds) if hours < 24
+
+        days = hours / 24
+        hours %= 24
+        return sprintf("%i days %i:%02i:%02i", days, hours, minutes, int_seconds)
       end
     end
   end