Rename SubtreeWildcardSymbol to WildcardSymbol across whole project.

...o/src/arbology/exact/ExactNonlinearTreePatternAutomaton.h

alib2algo/src/arbology/exact/ExactTreePatternAutomaton.h

alib2algo/src/tree/generate/RandomTreeFactory.cpp

alib2data/src/alphabet/SymbolClasses.h

alib2data/src/alphabet/SymbolFeatures.h

alib2data/src/alphabet/WildcardSymbol.cpp

alib2data/src/alphabet/WildcardSymbol.h

alib2data/src/alphabet/xml/WildcardSymbol.cpp

alib2data/src/alphabet/xml/WildcardSymbol.h

alib2data/src/tree/common/TreeFromXMLParser.h

alib2data/src/tree/ranked/PrefixRankedBarNonlinearPattern.h

alib2data/src/tree/ranked/PrefixRankedBarPattern.h

alib2data/src/tree/ranked/PrefixRankedNonlinearPattern.h

alib2data/src/tree/ranked/PrefixRankedPattern.h

alib2data/src/tree/ranked/RankedNonlinearPattern.h

alib2data/src/tree/ranked/RankedPattern.h

alib2data/src/tree/unranked/UnrankedNonlinearPattern.h

alib2data/src/tree/unranked/UnrankedPattern.h

alib2data/test-src/tree/PatternTest.cpp

alib2data/test-src/tree/TreeTest.cpp