simplify includes in trees

acast2/src/cast/TreeCastVisitor.cpp

acast2/src/cast/TreeToStringCastVisitor.cpp

alib2data/src/XmlApi.cpp

alib2data/src/object/ObjectBase.h

alib2data/src/tree/Tree.h

alib2data/src/tree/TreeBase.h

alib2data/src/tree/TreeClasses.h

alib2data/src/tree/TreeFeatures.h

alib2data/src/tree/TreeFromRawParser.cpp

alib2data/src/tree/TreeFromRawParser.h

alib2data/src/tree/TreeFromXMLParser.cpp

alib2data/src/tree/TreeFromXMLParser.h

alib2data/src/tree/TreeToRawComposer.cpp

alib2data/src/tree/TreeToRawComposer.h

alib2data/src/tree/TreeToXMLComposer.cpp

alib2data/src/tree/TreeToXMLComposer.h

alib2data/test-src/tree/PatternTest.cpp

alib2data/test-src/tree/TreeTest.cpp

tniceprint/src/tniceprint.cpp