Avoid C typedefs.

src/html_common.hh

@@ -123,7 +123,8 @@ struct DilloHtmlImage {
    std::shared_ptr< DilloImage > image;
 };
 
-typedef struct {
+struct DilloHtmlState
+{
    DilloHtmlParseMode parse_mode;
    DilloHtmlTableMode table_mode;
    DilloHtmlTableBorderMode table_border_mode;
@@ -144,7 +145,7 @@ typedef struct {
       have to be "handed over" (see Html_add_indented and
       Html_eventually_pop_dw). */
    bool hand_over_break;
-} DilloHtmlState;
+};
 
 /*
  * Classes