Minor Main.py changes

Hello!

I changed some code, but I have some questions.
We don't really need to watch splashscreen (which is very long on my machine, about 10-15 seconds) when we are debugging. Right? So, why we are displaying debug status at the "splashscreen" state? Even if we show this message at another state, we really don't need it. Debug state is debug info too. So, I think we only need to write something like 
```Debug is enabled! Beware, strangers```
End user don't care about debug at all.

Also we don't need to store X window size and Y window size separately, when we have this information in a tuple.
Same with center coordinates.

And all this code need more refactoring.

For example:
We have this code in Main.py
```
level = Level(levelMap)
level.parseLevel()
```
and the same code in level.py!
```
levelMap = loadMapFile("level.map")
level = Level(levelMap)
level.parseLevel()
```