feat(emacs/lean-company): truncate string if it's longer than 90% of window-width
feat(emacs/lean-company): truncate string if it's longer than 90% of window-width

Also add "..." in the end

Close #137

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