Remove unneeded volatility, enabling more optimisations. Sound volatility is #define'd away, GUI volatility is simply removed.
GUI touch handling improvements.

* Don't select items defined with type HIDEN_TYPE. That's for items like the card capacity display.
* Don't change current_option and current_option_num until we're sure of what's going on.
* Don't select an item from another menu if you touch a phantom menu item below the last one of the active menu. For example, Video & audio's item 5 would call up the ROM loading dialog. This is now fixed.
* Handle NUMBER_SELECTION_TYPE and STRING_SELECTION_TYPE as invocations of CURSOR_RIGHT. This fixes the language selector not updating the language in the GUI when touched.
* Handle ACTION_TYPE. This fixes the Load cheat file menu item not working when touched.
Cheats: "The Touch Screen will not work, so press A." Remove this tidbit, as it now works.