Revert back to using system.datestr() for preferred short date display output

Stripped trailing whitespace

xtrn/minesweeper/minesweeper.js

@@ -394,11 +394,6 @@ function get_winners(level)
 	return list;
 }
 
-function datestr(t)
-{
-	return strftime("%b%m-%y", t);
-}
-
 function show_winners(level)
 {
 	console.clear();
@@ -445,7 +440,7 @@ function show_winners(level)
 			,game.width
 			,game.height
 			,game.mines
-			,datestr(game.end)
+			,system.datestr(game.end)
 			));
 		count++;
 		displayed++;
@@ -491,7 +486,7 @@ function show_log()
 		else
 			console.attributes = BG_CYAN;
 		console.print(format("%s  %-25s %1.2f %s %3ux%2ux%-3u %3s  %s\x01>\x01n\r\n"
-			,datestr(game.end)
+			,system.datestr(game.end)
 			,game.name
 			,calc_difficulty(game)
 			,secondstr(calc_time(game), true)
@@ -527,7 +522,7 @@ function show_best()
 		else
 			console.attributes = BG_CYAN;
 		console.print(format("%s  %1.2f  %s  %3ux%2ux%-3u %s\x01>\x01n\r\n"
-			,datestr(game.end)
+			,system.datestr(game.end)
 			,calc_difficulty(game)
 			,secondstr(calc_time(game), true)
 			,game.width, game.height, game.mines