new approach to specify constant symbols

...algo/src/arbology/exact/ExactPatternMatchingAutomaton.cpp

...algo/src/arbology/exact/ExactSubtreeMatchingAutomaton.cpp

alib2algo/src/automaton/transform/PDAToRHPDA.cpp

alib2algo/src/automaton/transform/RHPDAToPDA.cpp

alib2algo/src/grammar/convert/ToAutomatonBottomUp.cpp

...go/src/rte/convert/ToPostfixPushdownAutomatonGlushkov.cpp

alib2algo/src/tree/generate/RandomTreeFactory.cpp

alib2algo/test-src/grammar/convert/GrammarCFGtoPDATest.cpp

alib2data/src/alphabet/BarSymbol.cpp

alib2data/src/alphabet/BarSymbol.h

alib2data/src/alphabet/BlankSymbol.cpp

alib2data/src/alphabet/BlankSymbol.h

alib2data/src/alphabet/BottomOfTheStackSymbol.cpp

alib2data/src/alphabet/BottomOfTheStackSymbol.h

alib2data/src/alphabet/EndSymbol.cpp

alib2data/src/alphabet/EndSymbol.h

alib2data/src/alphabet/RankedSymbol.h

alib2data/src/alphabet/StartSymbol.cpp

alib2data/src/alphabet/StartSymbol.h

alib2data/src/alphabet/SubtreeWildcardSymbol.cpp