Fix HTTP Content-Type headers and meta tags to enforce UTF-8 encoding on all pages and error screens

hist.cgi

@@ -204,7 +204,7 @@ sub decode_hist {
 #-------------------------------------------------------------------------------
 # HTMLのヘッダー
 sub header {
-	print "Content-type: text/html\n\n";
+	print "Content-type: text/html; charset=UTF-8\n\n";
 	print <<"EOM";
 <html>
 <head>