Fix #2 changing speed.

[artemkonenko]

I changed the way of calculating the size of the additive to coordinates. Now it's speed_in_milliseconds * milliseconds_after_last_frame. That should avoid from different speed for different fps.

And I decrease required version of base package.

[geo2a]

Unfortunatly, you spoiled all raspberries by changing type of coordinates from Int to Double. The result: uncontrollable rounding errors in calculations and totally unpredictable game behavior :)

[geo2a]

Anyway, thank you for contributing!

[artemkonenko]

Yep, I was see, I want fix some unpredictable game behaviors and update this request in near future.

[geo2a]

Делать тебе нечего ;)

[artemkonenko]

Ну не бакалаврскую же писать, в конце-то концов)