Ingame timer display

Each battle has a timer which final count is shown in the score screen. However, such timer would be useful ingame as well, for various tests, mission "time trials", a way to check how long the game lasts for the player. Observer mode has such timer replacing the credits, a new timer which could be enabled with a rules tag under [GlobalControls] could for example be located here: http://mo.cncguild.net/sharo/timer.png Perhaps, with the tag enabled, the observer timer would be gone/moved for consistency.