feat(emacs): replace metavar '?M_n' with '_' in synthed expr
feat(emacs): replace metavar '?M_n' with '_' in synthed expr

leanprover-community/lean,Kha/lean,sp3ctum/lean,avigad/lean,htzh/lean,c-cube/lean,leanprover/lean,fpvandoorn/lean,fpvandoorn/lean2,leanprover/lean,UlrikBuchholtz/lean,sp3ctum/lean,johoelzl/lean,javra/lean,fpvandoorn/lean,levnach/lean,Kha/lean,fpvandoorn/lean,Kha/lean,eigengrau/lean,avigad/lean,fgdorais/lean,eigengrau/lean,fpvandoorn/lean2,leanprover-community/lean,soonhokong/lean,levnach/lean,digama0/lean,leodemoura/lean,sp3ctum/lean,soonhokong/lean,leodemoura/lean,fgdorais/lean,dselsam/lean,fgdorais/lean,rlewis1988/lean,c-cube/lean,johoelzl/lean,avigad/lean,leodemoura/lean,dselsam/lean,fpvandoorn/lean,leanprover-community/lean,sp3ctum/lean,levnach/lean,javra/lean,leanprover/lean,Kha/lean,javra/lean,fgdorais/lean,johoelzl/lean,c-cube/lean,rlewis1988/lean,leanprover-community/lean,eigengrau/lean,fpvandoorn/lean2,fpvandoorn/lean,avigad/lean,eigengrau/lean,soonhokong/lean-osx,c-cube/lean,johoelzl/lean,leanprover-community/lean,avigad/lean,leodemoura/lean,leanprover/lean,htzh/lean,javra/lean,htzh/lean,dselsam/lean,htzh/lean,c-cube/lean,johoelzl/lean,digama0/lean,soonhokong/lean-windows,levnach/lean,UlrikBuchholtz/lean,Kha/lean,johoelzl/lean,soonhokong/lean-windows,soonhokong/lean-windows,fpvandoorn/lean2,fgdorais/lean,soonhokong/lean,UlrikBuchholtz/lean,soonhokong/lean,rlewis1988/lean,rlewis1988/lean,soonhokong/lean-osx,soonhokong/lean-osx,levnach/lean,dselsam/lean,Kha/lean,eigengrau/lean,digama0/lean,htzh/lean,dselsam/lean,leodemoura/lean,rlewis1988/lean,digama0/lean,soonhokong/lean-osx,UlrikBuchholtz/lean,digama0/lean,soonhokong/lean-osx,digama0/lean,soonhokong/lean-windows,fpvandoorn/lean,dselsam/lean,leanprover-community/lean,leanprover/lean,rlewis1988/lean,leodemoura/lean,fpvandoorn/lean2,soonhokong/lean-windows,leanprover/lean,sp3ctum/lean,fgdorais/lean,UlrikBuchholtz/lean,avigad/lean,soonhokong/lean,javra/lean