define add-functions in ObjectList and set Field(x,y) to screenwidth and
length
Merge branch 'master' of https://github.com/M1812M/Inf-PP.git

Conflicts:
	IceAge-0.2.1/src/project/iceage/model/Field.java
	IceAge-0.2.1/src/project/iceage/model/ObjectList.java
Merge branch 'master' of https://github.com/M1812M/Inf-PP