Messages: try to fix API message handling

Passed timeout for messeages an popup's fired by yWeb API was not really
ok.
For popups now we have a setting with default value of 6 seconds timeout
Popups fired with ShowHint() use this as default. Value of 0 and -1
are ignored.
Messages fired with ShowMsg() should be fixed and interpret
value 0 or -1 as no timeout and will remain on the screen.

src/system/locals.h

@@ -2433,6 +2433,7 @@ typedef enum
 	LOCALE_TIMING_INFOBAR_RADIO,
 	LOCALE_TIMING_MENU,
 	LOCALE_TIMING_NUMERICZAP,
+	LOCALE_TIMING_POPUP_MESSAGES,
 	LOCALE_TIMING_VOLUMEBAR,
 	LOCALE_TMDB_API_KEY,
 	LOCALE_TMDB_ENABLED,