Recognise and ignore Doxygen group commands @{ and @}

Fixes #1750

Source/Doxygen/doxycommands.h

@@ -44,6 +44,8 @@ const int sectionIndicatorsSize = sizeof(sectionIndicators) / sizeof(*sectionInd
 const char *simpleCommands[] = {
   // the first line are escaped chars, except \~, which is a language ID command.
   "n", "$", "@", "\\", "&", "~", "<", ">", "#", "%", "\"", ".", "::",
+  // Member groups, which we currently ignore.
+  "{", "}",
   "endcond",
   "callgraph", "callergraph", "showinitializer", "hideinitializer", "internal",
   "nosubgrouping", "public", "publicsection", "private", "privatesection",

Source/Doxygen/doxyparser.h

@@ -238,7 +238,7 @@ private:
    * Method for Adding a Simple Command
    * Format: @command
    * Plain commands, such as newline etc, they contain no other data
-   *  \n \\ \@ \& \$ \# \< \> \%
+   *  \n \\ \@ \& \$ \# \< \> \% \{ \}
    */
   void addSimpleCommand(const std::string &theCommand, DoxygenEntityList &doxyList);
   /*