Update group tests so they run.

src/sudoku/group.rs

@@ -422,8 +422,11 @@ pub fn which_cell(x:u8, y:u8) -> u8 {
 
 #[cfg(test)]
 mod tests {
-    use crate::Group;
-    use crate::{for_cell, for_column, for_row};
+    use crate::sudoku::group::*;
+    // use crate::Group;
+    // use group::*;
+
+    // use crate::{for_cell, for_column, for_row};
 
     #[test]
     fn check_columns() {