support deleting entries, always tell file that entry information was changed.

lib/src/kdbx_dao.dart

@@ -51,6 +51,10 @@ extension KdbxDao on KdbxFile {
     move(group, recycleBin);
   }
 
+  void deleteEntry(KdbxEntry entry) {
+    move(entry, recycleBin);
+  }
+
   void move(KdbxObject kdbxObject, KdbxGroup toGroup) {
     assert(toGroup != null);
     kdbxObject.times.locationChanged.setToNow();

lib/src/kdbx_object.dart

@@ -97,7 +97,7 @@ abstract class KdbxObject extends KdbxNode {
   set isDirty(bool dirty) {
     if (dirty) {
       times.modifiedNow();
-      if (!isDirty && dirty) {
+      if (/*!isDirty && */ dirty) {
         file.dirtyObject(this);
       }
     }
@@ -112,7 +112,10 @@ abstract class KdbxObject extends KdbxNode {
     return el;
   }
 
-  void internalChangeParent(KdbxGroup parent) => _parent = parent;
+  void internalChangeParent(KdbxGroup parent) {
+    _parent = parent;
+    isDirty = true;
+  }
 }
 
 class KdbxUuid {