simplify includes, attach regexp alphabet only

alib2algo/src/automaton/convert/ToRegExpAlgebraic.cpp

alib2algo/src/automaton/convert/ToRegExpAlgebraic.h

alib2algo/src/automaton/convert/ToRegExpStateElimination.h

alib2algo/src/equations/RegularEquationSolver.cpp

alib2algo/src/equations/RegularEquationSolver.h

alib2algo/src/grammar/convert/ToRegExpAlgebraic.cpp

alib2algo/src/regexp/convert/ToAutomatonThompson.cpp

alib2algo/src/regexp/convert/ToAutomatonThompson.h

alib2algo/src/regexp/generate/RandomRegExpFactory.cpp

alib2algo/src/regexp/generate/RandomRegExpFactory.h

alib2algo/src/regexp/properties/RegExpEmpty.cpp

alib2algo/src/regexp/properties/RegExpEmpty.h

alib2algo/src/regexp/properties/RegExpEpsilon.cpp

alib2algo/src/regexp/properties/RegExpEpsilon.h

alib2algo/src/regexp/transform/RegExpAlternate.cpp

alib2algo/src/regexp/transform/RegExpAlternate.h

alib2algo/src/regexp/transform/RegExpConcatenate.cpp

alib2algo/src/regexp/transform/RegExpConcatenate.h

alib2algo/src/regexp/transform/RegExpDerivation.cpp

alib2algo/src/regexp/transform/RegExpDerivation.h