refactor cast capability to be fully dynamic

acast2/src/CastVisitorBase.hpp

acast2/src/acast.cpp

acast2/src/cast/AutomatonCastVisitor.cpp

acast2/src/cast/AutomatonCastVisitor.h

acast2/src/cast/GrammarCastVisitor.cpp

acast2/src/cast/GrammarCastVisitor.h

acast2/src/cast/RegExpCastVisitor.cpp

acast2/src/cast/RegExpCastVisitor.h

acast2/src/cast/TreeCastVisitor.cpp

acast2/src/cast/TreeCastVisitor.h

acast2/src/cast/TreeToStringCastVisitor.cpp

acast2/src/cast/TreeToStringCastVisitor.h

alib2data/src/CastApi.hpp

alib2data/src/automaton/FSM/CompactNFA.cpp

alib2data/src/automaton/FSM/EpsilonNFA.cpp

alib2data/src/automaton/FSM/ExtendedNFA.cpp

alib2data/src/automaton/FSM/MultiInitialStateNFA.cpp

alib2data/src/automaton/FSM/NFA.cpp

alib2data/src/regexp/formal/FormalRegExp.cpp

alib2data/src/regexp/unbounded/UnboundedRegExp.cpp