add options for grading all submissions of a specific problem 

(grafted from branch algo-bm 8ed1c0aa59eaf8e22e40fc765c1fba4ac88a34b5)

to grade all submissions of the specific problem, use ./script/grader grading prob [probname] --all-sub

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extra : source : 8ed1c0aa59eaf8e22e40fc765c1fba4ac88a34b5