fix: coding style and file format for chapter 9.

eBook/exercises/chapter_9/main_oddeven.go

@@ -1,13 +1,13 @@
-// test_oddeven.go
-package main
-
-import (
-	"fmt"
-	"./even/even"
-)
-
-func main() {
-	for i:=0; i<=100; i++ {
-		fmt.Printf("Is the integer %d even? %v\n", i, even.Even(i)) 
-	}
-}
+// test_oddeven.go
+package main
+
+import (
+	"./even/even"
+	"fmt"
+)
+
+func main() {
+	for i := 0; i <= 100; i++ {
+		fmt.Printf("Is the integer %d even? %v\n", i, even.Even(i))
+	}
+}