Target class changed to allow direct references between objects instead of referencing by their IDs.
Target changed to Targets. Now all targets are wrapped in an object.
Target class added. The purpose of this class is the same as Targets', but to be used when only one target exists.
'addTargets' method added to the Targets class.
Adapting classes to the new object referencing method
Adapting classes to the new object referencing method
Adapting classes to the new object referencing method
Merge branch 'master' into obj_reference_type_change

Conflicts:
	src/main/java/ixa/kaflib/Opinion.java
	src/main/java/ixa/kaflib/ReadWriteManager.java
Adapting classes to the new object referencing method
Indices removed
Input KAF document validity check
Comments added
Some stuff with spans
Index operations updated in WF.java
Relation debug XML comments updated
Copy constructors implemented
Merge() implemented. It merges two KAF documents.
Version changed to 2.0-SNAPSHOT
Changed the way of referencing objects. Now direct references are used instead of ID values.

Merge branch 'obj_reference_type_change'
SRL added