ULTIMA8: Optional stacks automerging

[i30817]

Reading the changes for ultima 8 reminded me of a PR i made some years ago to exult to make the stack handling of stackable items more ergonomic.

In short i added a boolean config variable and a key modifier to 'not show' the stack slider that shows when you move stacks or merge them. With the variable set to the default, the stack slider showed, unless you were pressing the key (CTRL iirc), in which case it merged/dropped the whole stack. With it on, the only way to show the stack slider was pressing the key when dropping the stack.

I don't know if u8 already has this change (i don't remember it but i guess no).

Anyway this is a RFE. It makes managing the inventory slightly less annoying in ultima 7, and i'd guess it would do the same for u8 (you can go even further and automerge when dropped in containers, but that's both more complex and something of a big change).