feat(builtin): define list, cons, nil and prove basic theorems
feat(builtin): define list, cons, nil and prove basic theorems

Signed-off-by: Leonardo de Moura <7610bae85f2b530654cc716772f1fe653373e892@microsoft.com>

Kha/lean,leodemoura/lean,levnach/lean,eigengrau/lean,leanprover/lean,fgdorais/lean,soonhokong/lean-osx,dselsam/lean,UlrikBuchholtz/lean,digama0/lean,soonhokong/lean-windows,levnach/lean,Kha/lean,fpvandoorn/lean2,dselsam/lean,fpvandoorn/lean,johoelzl/lean,avigad/lean,Kha/lean,avigad/lean,UlrikBuchholtz/lean,dselsam/lean,htzh/lean,fgdorais/lean,johoelzl/lean,fpvandoorn/lean,leodemoura/lean,leanprover-community/lean,UlrikBuchholtz/lean,soonhokong/lean,soonhokong/travis_test,soonhokong/lean-osx,avigad/lean,eigengrau/lean,digama0/lean,johoelzl/lean,codyroux/lean0.1,rlewis1988/lean,rlewis1988/lean,leanprover-community/lean,soonhokong/lean,leanprover-community/lean,leodemoura/lean,c-cube/lean,htzh/lean,leodemoura/lean,soonhokong/lean-windows,eigengrau/lean,leanprover/lean,avigad/lean,soonhokong/lean,fpvandoorn/lean,johoelzl/lean,codyroux/lean0.1,fgdorais/lean,leodemoura/lean,fpvandoorn/lean2,sp3ctum/lean,javra/lean,leanprover/lean,rlewis1988/lean,Kha/lean,levnach/lean,soonhokong/lean,fpvandoorn/lean,soonhokong/lean,digama0/lean,soonhokong/travis_test,johoelzl/lean,c-cube/lean,leanprover-community/lean,avigad/lean,soonhokong/lean-windows,sp3ctum/lean,soonhokong/travis_test,eigengrau/lean,Kha/lean,c-cube/lean,fgdorais/lean,fpvandoorn/lean2,c-cube/lean,digama0/lean,soonhokong/lean-osx,sp3ctum/lean,fpvandoorn/lean2,leanprover/lean,javra/lean,soonhokong/travis_test,htzh/lean,dselsam/lean,levnach/lean,digama0/lean,javra/lean,eigengrau/lean,dselsam/lean,avigad/lean,codyroux/lean0.1,UlrikBuchholtz/lean,johoelzl/lean,leodemoura/lean,soonhokong/lean-osx,fgdorais/lean,leanprover-community/lean,fpvandoorn/lean2,htzh/lean,rlewis1988/lean,codyroux/lean0.1,htzh/lean,leanprover/lean,rlewis1988/lean,soonhokong/lean-windows,leanprover/lean,javra/lean,c-cube/lean,javra/lean,sp3ctum/lean,sp3ctum/lean,soonhokong/lean-osx,fpvandoorn/lean,soonhokong/lean-windows,rlewis1988/lean,dselsam/lean,leanprover-community/lean,UlrikBuchholtz/lean,levnach/lean,fgdorais/lean,digama0/lean,fpvandoorn/lean,Kha/lean