* iface/dve2/dve2.cc, iface/dve2/dve2.hh,
src/kripke/kripkeexplicit.cc, src/kripke/kripkeexplicit.hh,
src/ltlvisit/contain.cc, src/ltlvisit/contain.hh,
src/ltlvisit/simplify.cc, src/ltlvisit/simplify.hh,
src/tgba/bddprint.cc, src/tgba/bddprint.hh, src/tgba/formula2bdd.cc,
src/tgba/formula2bdd.hh, src/tgba/taatgba.cc, src/tgba/taatgba.hh,
src/tgba/tgbagraph.hh, src/tgbaalgos/compsusp.cc,
src/tgbaalgos/compsusp.hh, src/tgbaalgos/lbtt.cc,
src/tgbaalgos/lbtt.hh, src/tgbaalgos/ltl2tgba_fm.cc,
src/tgbaalgos/ltl2tgba_fm.hh, src/tgbaalgos/randomgraph.cc,
src/tgbaalgos/randomgraph.hh, src/tgbaalgos/translate.cc,
src/tgbaalgos/translate.hh, src/tgbaalgos/word.cc,
src/tgbaalgos/word.hh: Pass shared_ptr to functions by const ref.