Converted zero/max buttons to +-10 buttons

[Zarkonnen]

As discussed in email, the big buttons now do +-10. I've also made the code a bit more generic and hence shorter. :)

[Zarkonnen]

Also added functionality to take all loot of a type at once when you have to drop items. Let me know if this is a useful addition.

[Continuities]

I'm not exactly sure how the Take All button functions...
Since the dropdown only appears when the player attempts to pick something up that weighs too much, clicking Take All can't confer the information about what (and how many) to drop to make room for the new thing.

For example: I'm wandering the world with a full bag, and I want to pick up some Cured Meat from a pile of 10. If I click on the Cured Meat, the "drop" dropdown appears, now with the Take All option at the top. What is expected to happen if I click Take All? Right now, apparently nothing? I do like the idea of a Take All option, but I'm not sure it belongs in this dropdown.

[Zarkonnen]

So the pain point Take All is meant to fix is the following:

When you want to pick up lots of things quickly and have enough space, this is fast and easy: just click the button rapidly. However, as soon as you run out of space, it gets really slow: you have to keep on selecting things to drop. For example, finding 10 cured meat and wanting to replace your 10 cloth with them feels like it takes forever.

So "take all" turns up when there's not enough space to pick up an item. If you click it, it reopens the drop menu, but this time with drop quantities high enough for then taking all items. So if there's still 5 cured meat left on the floor, and you have 5 cloth, it will say cloth x5 and let you switch them out all at once.

("This is a bad way of fixing this pain point" is a valid response. :D)

[Continuities]

Ahaaaaaa, I get it now. I agree that this change addresses a problem in the UI, but it's not terribly intuitive (as evidenced by my confusion). The worst part is, I'm not entirely sure how to solve this problem in an intuitive manner.

[Zarkonnen]

Agreed. Because of slight git fail, this pull request contains both this feature and a perfectly good fix to the up/down buttons. I'll look into fixing that.

[Zarkonnen]

OK, this pull request now only converts the zero/max buttons to +-10 buttons.

[Zarkonnen]

Woo! Now working on medicine.