feat(metavar): improve apply_local_context
feat(metavar): improve apply_local_context

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

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