simplify compare methods

alib2data/src/container/ObjectsMap.cpp

alib2data/src/container/ObjectsPair.cpp

alib2data/src/container/ObjectsSet.cpp

alib2data/src/container/ObjectsVector.cpp

alib2data/src/grammar/ContextFree/CFG.cpp

alib2data/src/grammar/ContextFree/CNF.cpp

alib2data/src/grammar/ContextFree/EpsilonFreeCFG.cpp

alib2data/src/grammar/ContextFree/GNF.cpp

alib2data/src/grammar/ContextFree/LG.cpp

alib2data/src/grammar/ContextSensitive/CSG.cpp

...ta/src/grammar/ContextSensitive/NonContractingGrammar.cpp

alib2data/src/grammar/Regular/LeftLG.cpp

alib2data/src/grammar/Regular/LeftRG.cpp

alib2data/src/grammar/Regular/RightLG.cpp

alib2data/src/grammar/Regular/RightRG.cpp

...mar/Unrestricted/ContextPreservingUnrestrictedGrammar.cpp

alib2data/src/grammar/Unrestricted/UnrestrictedGrammar.cpp

alib2data/src/label/LabelSetLabel.cpp

alib2data/src/string/CyclicString.cpp

alib2data/src/string/Epsilon.cpp