fix als node reuse error in the tiling optimization
add cost_hint for all shuffle exprs
fix some apps, including als, three regression, disdca_svm, cg
fix visit_DotExpr node expr must be a list
fix forest and reshape test
fix concatinate cannot concat two zero-dim array error
fix concatinate error when two arrays are one-dim array
Merge pull request #194 from MaggieQi/master

fix als node reuse error in the tiling optimization