Add --reformat and --reformat-all flags

src/files.rs

@@ -175,6 +175,12 @@ impl Files {
         Ok(())
     }
 
+    pub fn mark_main_dirty(&mut self) {
+        if let Some(file) = self.files.get_mut(0) {
+            file.dirty = true;
+        }
+    }
+
     pub fn mark_all_dirty(&mut self) {
         for file in self.files.iter_mut() {
             file.dirty = true;