make unranked trees use smart pointers

alib2algo/src/arbology/exact/ExactPatternMatch.cpp

alib2algo/src/arbology/exact/ExactSubtreeMatch.cpp

alib2algo/src/tree/generate/RandomTreeFactory.cpp

alib2data/src/tree/common/TreeFromXMLParser.cpp

alib2data/src/tree/common/TreeFromXMLParser.h

alib2data/src/tree/ranked/RankedNode.cpp

alib2data/src/tree/ranked/RankedNode.h

alib2data/src/tree/unranked/PrefixBarTree.cpp

alib2data/src/tree/unranked/UnrankedNode.cpp

alib2data/src/tree/unranked/UnrankedNode.h

alib2data/src/tree/unranked/UnrankedNonlinearPattern.cpp

alib2data/src/tree/unranked/UnrankedNonlinearPattern.h

alib2data/src/tree/unranked/UnrankedPattern.cpp

alib2data/src/tree/unranked/UnrankedPattern.h

alib2data/src/tree/unranked/UnrankedTree.cpp

alib2data/src/tree/unranked/UnrankedTree.h

alib2raw/src/tree/TreeFromRawParser.cpp

alib2raw/src/tree/TreeFromRawParser.h

alib2str/src/tree/TreeFromStringParser.cpp

alib2str/src/tree/TreeFromStringParser.h