Apply combinators

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The apply combinators apply a single quotation to multiple values. The @ suffix signifies application.

Two quotations:
• bi@ ( x y quot -- )
• 2bi@ ( w x y z quot -- )
Three quotations:
• tri@ ( x y z quot -- )
• 2tri@ ( u v w y x z quot -- )
A pair of utility words built from bi@:
• both? ( x y quot -- ? )
• either? ( x y quot -- ? )