better FPS indicator

[fabio]

1) FPS should also be enabled with a checkbox in the settings menu, other than pressing SHIFT-F, so one can easily find it to check the effect of playing with graphic options;

2) FPS indicator should be moved, currently is overlapped to the food indicator, maybe also using a better font.

[historic_bruno]

I moved the FPS counter down a bit and made its background dark, should be easier to read now in-game (where it matters). I'm not sure about your other suggestion :)

[fabio]

I was thinking at putting it left to the MENU, so that also it doesn't overlap with the profiler.

[Kieran P]

The FPS is now below the top bar, and on top of a black background for easy readability. As for the menu option, we don't really need it, SHIFT+F works just fine for now.