SpriteBatch optimalizálás

Tesztelésre
This is our performance log (iOS 4S release configuration) measured by Instruments:
![performance](https://cloud.githubusercontent.com/assets/8473472/4093832/8e2b1d86-2fa1-11e4-9de2-e519ddc60d06.png)

Text rendering is responsible for ~40% of the CPU usage, in debug configuration this may cause low frame rate.