Merge branch 'master' into jgrpp

# Conflicts:
#	src/lang/afrikaans.txt
#	src/lang/basque.txt
#	src/lang/belarusian.txt
#	src/lang/brazilian_portuguese.txt
#	src/lang/bulgarian.txt
#	src/lang/catalan.txt
#	src/lang/croatian.txt
#	src/lang/czech.txt
#	src/lang/danish.txt
#	src/lang/dutch.txt
#	src/lang/english.txt
#	src/lang/english_AU.txt
#	src/lang/english_US.txt
#	src/lang/estonian.txt
#	src/lang/finnish.txt
#	src/lang/french.txt
#	src/lang/gaelic.txt
#	src/lang/galician.txt
#	src/lang/german.txt
#	src/lang/greek.txt
#	src/lang/hebrew.txt
#	src/lang/hungarian.txt
#	src/lang/icelandic.txt
#	src/lang/indonesian.txt
#	src/lang/irish.txt
#	src/lang/italian.txt
#	src/lang/japanese.txt
#	src/lang/korean.txt
#	src/lang/latin.txt
#	src/lang/latvian.txt
#	src/lang/lithuanian.txt
#	src/lang/luxembourgish.txt
#	src/lang/norwegian_bokmal.txt
#	src/lang/norwegian_nynorsk.txt
#	src/lang/polish.txt
#	src/lang/portuguese.txt
#	src/lang/romanian.txt
#	src/lang/russian.txt
#	src/lang/serbian.txt
#	src/lang/simplified_chinese.txt
#	src/lang/slovak.txt
#	src/lang/slovenian.txt
#	src/lang/spanish.txt
#	src/lang/spanish_MX.txt
#	src/lang/swedish.txt
#	src/lang/tamil.txt
#	src/lang/thai.txt
#	src/lang/traditional_chinese.txt
#	src/lang/turkish.txt
#	src/lang/ukrainian.txt
#	src/lang/unfinished/persian.txt
#	src/lang/vietnamese.txt
#	src/lang/welsh.txt
#	src/rail_cmd.cpp
#	src/station_cmd.cpp

src/window.cpp

@@ -39,6 +39,7 @@
 #include "framerate_type.h"
 #include "network/network_func.h"
 #include "guitimer_func.h"
+#include "news_func.h"
 
 #include "safeguards.h"
 
@@ -3408,6 +3409,17 @@ restart_search:
 	}
 }
 
+/**
+ * Delete all messages and their corresponding window (if any).
+ */
+void DeleteAllMessages()
+{
+	InitNewsItemStructs();
+	InvalidateWindowData(WC_STATUS_BAR, 0, SBI_NEWS_DELETED); // invalidate the statusbar
+	InvalidateWindowData(WC_MESSAGE_HISTORY, 0); // invalidate the message history
+	DeleteWindowById(WC_NEWS_WINDOW, 0); // close newspaper or general message window if shown
+}
+
 /**
  * Delete all windows that are used for construction of vehicle etc.
  * Once done with that invalidate the others to ensure they get refreshed too.