feat(library/data/finset/basic.lean): add lots of theorems, do minor renaming
feat(library/data/finset/basic.lean): add lots of theorems, do minor renaming

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