This makes it so arrow keys/numpad can control screen shift when it's available.
When this preference is enabled, #482 will not be an issue (Fix#482). But the player will also miss out on cases where adjacent targeting would be a good thing. I haven't done anything smart to determine whether one mode or the other is better on a case-by-case basis.
* Changed shop purchase sound effects where Yum! definitely didn't fit. For alchemy, mage spells, and priest spells, I made the sound the same as the sound when you perform those actions. I figure this actually makes sense because the teacher would show you how to do the thing.
* For skill training, I made the sound be the same as leveling up. I think this makes sense.
* When something is too heavy to pick up, the "Argh!" labeled as 'Action Failure' in the editor sound picker makes a lot of sense--you tried to pick it up and were frustrated.
* I changed beep() so every platform just plays sound effect 1, the one labeled "low beep" [here](http://openboe.com/docs/editor/appendix/Sounds.html) that's labeled "Cancel target lock" in the editor picker. I think this reasonable.
* Removed `ding()` which was an unused alias for `beep()`
For the recharge spell, there is now a chance for the item to melt if you try to charge it too much.
For recharge shops, it is now possible to configure how much they are willing to charge an item,
as well as how many charges are given per payment.
Pretty much all of these fall into one of two categories:
* Variables that are obviously unneeded and in many cases completely unused – probably remnants of old code that was rewritten. These ones were deleted.
* Variables that look like they should be used but aren't. These ones have been suppressed, with a TODO message added as a reminder to investigate them in more detail later.
Since we can't directly use C++11 attributes, I've chosen BOOST_FALLTHROUGH to annotate intentional fallthroughs.
Thanks to @fosnola for spotting a missing break, which triggered this.
