Skapat model-paketet och lagt till klasser enligt tidigare diskussion
fler metoder till model-paketet samt flyttat alla klasser ur util
lite skit
Merge branch 'master' of https://github.com/velixo/XL

Conflicts:
	src/expr/Num.java
	src/gui/Adjustment.java
	src/gui/NumberAdjustment.java
	src/gui/menu/Adjustment.java
	src/gui/menu/NumberAdjustment.java
	src/model/ExprSlot.java
	src/model/MainSheet.java
	src/model/Slot.java
	src/model/SlotFactory.java
	src/model/SlotMap.java
	src/model/TextSlot.java
	src/util/Adjustment.java
	src/util/NumberAdjustment.java