(svn r9089) -Codechange: Remove the 32 widgets limit on News Options window.

-Codechange: Use the newly created WWT_TEXT widget.
-Cleanup: remove a lot of magic numbers, make the whole window more flexible, with now the possibility to easily add new type of news events.
Thanks glx for ideas from an old patch

src/news.h

@@ -31,16 +31,17 @@ void InitNewsItemStructs();
 VARDEF NewsItem _statusbar_news_item;
 
 enum NewsType {
-	NT_ARRIVAL_PLAYER = 0,
-	NT_ARRIVAL_OTHER  = 1,
-	NT_ACCIDENT       = 2,
-	NT_COMPANY_INFO   = 3,
-	NT_ECONOMY        = 4,
-	NT_ADVICE         = 5,
-	NT_NEW_VEHICLES   = 6,
-	NT_ACCEPTANCE     = 7,
-	NT_SUBSIDIES      = 8,
-	NT_GENERAL        = 9,
+	NT_ARRIVAL_PLAYER,
+	NT_ARRIVAL_OTHER,
+	NT_ACCIDENT,
+	NT_COMPANY_INFO,
+	NT_ECONOMY,
+	NT_ADVICE,
+	NT_NEW_VEHICLES,
+	NT_ACCEPTANCE,
+	NT_SUBSIDIES,
+	NT_GENERAL,
+	NT_END,
 };
 
 enum NewsMode {