feat(hott/trunc): clean up some theorems, prove some basic theorems
feat(hott/trunc): clean up some theorems, prove some basic theorems

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