Revert "temporarily remove is_winnable because it doesn't work"

This reverts commit 5a52f2ab7a.

klondike-cli/src/main.rs

@@ -4,8 +4,8 @@ use klondike::{
 	KlondikePile, KlondikePileStack, KlondikeStats, SkipCards, Tableau, TableauStack,
 };
 
-// #[cfg(test)]
-// mod test;
+#[cfg(test)]
+mod test;
 
 use std::fmt::Display;
 struct Displayed<T>(T);