separate files and fix newline bug

todo.c

@@ -0,0 +1,23 @@
+#include "todo.h"
+#include <string.h>
+#include <stdio.h>
+
+TodoItem create_todo(const char *title) {
+  TodoItem item;
+  strncpy(item.title, title, MAX_TODO_TITLE_LENGTH);
+  item.completed = false;
+  return item;
+}
+
+void mark_todo(TodoItem *item, bool completed) {
+  (*item).completed = completed;
+}
+
+void print_todo(TodoItem *item) {
+  printf("%s - ", item->title);
+  if (item->completed) {
+    printf("Completed\n");
+  } else {
+    printf("Not Completed\n");
+  }
+}