feat(library/standard/logic): add imp_or theorems
feat(library/standard/logic): add imp_or theorems

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

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