Argument migration

Add a DSL to migrate options to different names, migrate them from either being manually passed or from tabs and print a warning telling users to use the new name. Also, migrate `wget` as an example.

CC @adamv @mistydemeo @jacknagel @tdsmith @asparagui for thoughts and review.
Can use `refute_empty`, which gives a better failure message that plain `assert`. Though this assertion is implicit in the following assertions.