remove click sound when clicking on dialog message.

This was used to add also a sound when closing menu (since menu do
sounds for every other actions)

I will look it later how differentiate the two cases.

src/construct_dialog.cpp

@@ -722,7 +722,6 @@ int dialog::process(dialog_process_info &info)
 	//left-clicking outside of a drop-down or context-menu should close it
 	if (info.new_left_button && !info.left_button) {
 		if (standard_buttons_.empty() && !point_in_rect(mousex,mousey, menu_->location())) {
-			sound::play_UI_sound(game_config::sounds::button_press);
 			return CLOSE_DIALOG;
 			}
 	}