move string xml api code to seperate files

alib2data/src/PrimitiveRegistrator.cpp

alib2data/src/string/CyclicString.cpp

alib2data/src/string/CyclicString.h

alib2data/src/string/Epsilon.cpp

alib2data/src/string/Epsilon.h

alib2data/src/string/LinearString.cpp

alib2data/src/string/LinearString.h

alib2data/src/string/StringBase.h

alib2data/src/string/common/StringFromXMLParser.h

alib2data/src/string/common/StringToXMLComposer.h

alib2data/src/string/xml/CyclicString.cpp

alib2data/src/string/xml/CyclicString.h

alib2data/src/string/xml/Epsilon.cpp

alib2data/src/string/xml/Epsilon.h

alib2data/src/string/xml/LinearString.cpp

alib2data/src/string/xml/LinearString.h

alib2data/src/string/xml/common/StringFromXmlParserCommon.h

alib2data/src/string/xml/common/StringToXmlComposerCommon.h

alib2data/test-src/string/StringTest.cpp

...experimental/src/string/LinearStringTerminatingSymbol.cpp