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/gui/widget/hintbox.cpp

@@ -196,6 +196,10 @@ int CHintBox::exec()
 	neutrino_msg_t msg;
 	neutrino_msg_data_t data;
 	int res = messages_return::none;
+
+	if (timeout == NO_TIMEOUT || timeout == 0)
+		timeout = HINTBOX_DEFAULT_TIMEOUT;
+
 	uint64_t timeoutEnd = CRCInput::calcTimeoutEnd( timeout );
 
 	if (timeout > 0)