add Memory::ResetUserDict() for librime-lua release user_dict before sync data

src/rime/algo/syllabifier.h

@@ -20,7 +20,7 @@ class Corrector;
 using SyllableId = int32_t;
 
 struct EdgeProperties : SpellingProperties {
-  EdgeProperties(SpellingProperties sup) : SpellingProperties(sup) {};
+  EdgeProperties(SpellingProperties sup) : SpellingProperties(sup){};
   EdgeProperties() = default;
   bool is_correction = false;
 };

src/rime/gear/memory.cc

@@ -86,6 +86,10 @@ Memory::~Memory() {
   unhandled_key_connection_.disconnect();
 }
 
+void Memory::ResetUserDict() {
+  user_dict_.reset();
+}
+
 bool Memory::StartSession() {
   return user_dict_ && user_dict_->NewTransaction();
 }

src/rime/gear/memory.h

@@ -47,6 +47,7 @@ class Memory {
   UserDictionary* user_dict() const { return user_dict_.get(); }
 
   const Language* language() const { return language_.get(); }
+  void ResetUserDict();
 
  protected:
   void OnCommit(Context* ctx);