moved render methods

Moved the methods responsible for rendering from Core.java and
Player.java to RenderLogic.java !
Field graphics

Graphics are now loaded from Environment.png and rendered correctly.
Also fixes up-down movement inversion.
Chunks fix

- Chunks are now found correctly if you ask what for it by a position
inside of it.
- added missing field types to FieldType.java
- minor performance improvement in Chunks.java by sparing one loop
- removed useless line in Field.java
Merge pull request #4 from igwb/mytl

Merge: mytl > master
Merge pull request #5 from igwb/master

Merge: mytl < master