run commands only once per set of parameters they use

[c-cube]

My use case is a bit different than in #637 but I think the solution could be the same.

Basically I want to run command "foo", "bar", and "baz {A} {B} {C}" with parameters A, B, C. Currently "foo" and "bar" are run once for each combination of A, B, and C, which is inefficient and clutters the output. Instead, "foo" and "bar" should run only once each.

It could be done either by, after expanding all combinations, deduplicating commands (but then showing parameters is harder); or detecting which subset of parameter/scans each command takes and computing only the relevant combinations.