remove no-usedOnce for BackwardsCompatibility.tw since it doesn't actually do...

remove no-usedOnce for BackwardsCompatibility.tw since it doesn't actually do anything important anymore (and backwardsCompatibility.js is already exempt).

src/data/backwardsCompatibility/BackwardsCompatibility.tw

 :: Backwards Compatibility [nobr]
 
-/* no-usedOnce disabling checking for only used once instances in this file */
 <<set $nextButton = "Continue", $nextLink = "Main", $returnTo = "Main">>
 
 <<run App.Update.setNonexistantProperties(V, App.Data.defaultGameStateVariables)>>