feat(library/tactic): refine repeat and repeat_at_most tacticals
feat(library/tactic): refine repeat and repeat_at_most tacticals

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

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