some general fixes and improvements

The engine is much faster now due to dramatically (ca. 20 times) fast…

…er rendering and a faster collision detection

A few general improvements and bugfixes.

Added the RectangleCreator and some general changes and improvements

Mainly fixing the rotation stuffsome other minor and maor changes des…

…cribed in the 0.15.0 release.

Made the starting of a Game easier and better

Added resizability with a correct curosr position shifting

Some minor improvements and new features, detailed list when releasei…

…ng 0.15.0

New features:

- Serialization
- WindowClosing hooks
- Screenshots
- Multi-lang support
- Fix mouse input

Some other minor changes and improvements
Improve performance by using images inserted of primitives

Improve the performance by using a lightweight JPanel instead of the …

…heavyweight Canvas