Implement a new module command that is called right before cosing the virtual machine to allow modules to release resources manually.

Should fix a possible crash in the IRC plugin which was caused by the Session destructor to be called recursively when cleaned automatically by the VM.

modules/irc/Module.cpp

@@ -99,6 +99,15 @@ static void OnSquirrelTerminate()
     NullFunction().ReleaseGently();
 }
 
+/* ------------------------------------------------------------------------------------------------
+ * The virtual machined is about to be closed. Last chance to release anything manually.
+*/
+static void OnSquirrelClosing()
+{
+    // Terminate all sessions, if any
+    SessionTerminate();
+}
+
 /* ------------------------------------------------------------------------------------------------
  * The virtual machined was closed and all memory associated with it was released.
 */
@@ -106,8 +115,6 @@ static void OnSquirrelReleased()
 {
     // Release the current virtual machine, if any
     DefaultVM::Set(nullptr);
-    // Terminate all sessions, if any
-    SessionTerminate();
 }
 
 /* ------------------------------------------------------------------------------------------------
@@ -141,6 +148,10 @@ static uint8_t OnPluginCommand(uint32_t command_identifier, CCStr message)
         {
             OnSquirrelTerminate();
         } break;
+        case SQMOD_CLOSING_CMD:
+        {
+            OnSquirrelClosing();
+        } break;
         case SQMOD_RELEASED_CMD:
         {
             OnSquirrelReleased();