move to_string and from_string to ext namespace

aconvert2/src/DotConverter.h

aconvert2/src/TikZConverter.h

alib2algo/src/automaton/transform/PDAToRHPDA.cpp

alib2algo/src/grammar/properties/NonterminalUnitRuleCycle.h

alib2cli/src/ast/statements/SingleStatement.h

alib2cli/src/command/SetCommand.h

alib2cli/src/parser/Parser.h

alib2common/src/abstraction/ImmediateRegistry.hpp

alib2common/src/abstraction/PrimitiveRegistrator.cpp

alib2common/src/abstraction/UnaryOperationAbstraction.hpp

alib2common/src/core/components.hpp

alib2common/src/core/xmlApi.hpp

alib2common/src/measurements/MeasurementResultsXml.cpp

alib2common/src/primitive/Double.cpp

alib2common/src/primitive/Integer.cpp

alib2common/src/primitive/Unsigned.cpp

alib2common/src/primitive/UnsignedLong.cpp

alib2common/test-src/core/DispatchTest.cpp

alib2data/src/alphabet/NonlinearVariableSymbol.h

alib2data/src/automaton/FSM/CompactNFA.h