1.2.0 - New Leaderboards, Steam Overlay

This update makes a significant change to the Minesweeper Ultimate leaderboards. Leaderboards now consider milliseconds as well as whole seconds. This is to make the leaderboards more competitive. The in-game clock has also been updated to display milliseconds.

I have also added functionality so that the Steam overlay can be shown in-game. Press your usual key combination (typically SHIFT + TAB) to toggle the overlay.

These changes should work the same for all users. Please let me know if there are any problems!