Adamantium zero arity

[mbj]

This PR fixes a case where veritas is memoizing a method that has a nonzero arity.

It includes two commits where only one should end up in master.

• 4cd0456 fixes the problem
• d08e29c Uses adamantium from current master, with the zero arity assertion. To make reproduction easy. And can be savely ignored as adamantium with the assertion will be released soon (?)

As there is no git source for reek that contains the Irresponsible module fix and is compatible to heckle ci is subjected to fail. The reek issue needs to be addressed as currently reek ^ heckle .

[dkubb]

It looks like Enumerable#to_set does actually take arguments, and since I don't really like changing the interface of overridden instance methods I may just avoid memoizing it altogether.