remove GrammarFeatures and StringFeatures header file

...o_experimental/src/grammar/parsing/AbsorbTerminalSymbol.h

...lgo_experimental/src/grammar/parsing/CornerSubstitution.h

...xperimental/src/grammar/parsing/DeterministicLL1Grammar.h

...go_experimental/src/grammar/parsing/ExtractRightContext.h

...perimental/src/grammar/parsing/HandleFirstFirstConflict.h

...erimental/src/grammar/parsing/HandleFirstFollowConflict.h

alib2algo_experimental/src/grammar/parsing/LeftFactorize.h

...algo_experimental/src/grammar/parsing/common/Substitute.h

alib2data/src/alphabet/Symbol.h

alib2data/src/grammar/ContextFree/CFG.h

alib2data/src/grammar/ContextFree/CNF.h

alib2data/src/grammar/ContextFree/EpsilonFreeCFG.h

alib2data/src/grammar/ContextFree/GNF.h

alib2data/src/grammar/ContextFree/LG.h

alib2data/src/grammar/ContextSensitive/CSG.h

...data/src/grammar/ContextSensitive/NonContractingGrammar.h

alib2data/src/grammar/GrammarFeatures.h

alib2data/src/grammar/Regular/LeftLG.h

alib2data/src/grammar/Regular/LeftRG.h

alib2data/src/grammar/Regular/RightLG.h