Version alpha 0.09

This is supposed to be a 1:1 port of Flashpunk to C#/MonoGame.

Things that work so far:

- adding entities to world
- rendering entities
- entitiy layers
- updating entities
- basic Image class
- basic animated Spritemap
- basic Background Class
- basic Tilemap Class (NOTE: 0 is considered empty tile and 1 is first tile)
- Hitbox collision detection (no support for masks)
- Keyboard input (NOTE: Key class is replaced with Keys class)