Additional vendor check for keys and scrolls

[sorc653]

The vendor selected for each act doesn't always have keys or scrolls, so we have to go to another vendor to do so.

This PR adds an additional check for purchasing keys and scrolls to ensure we don't run out. It also adds an option to return to town if we run out of keys. And it will only pick up keys if that option is enabled, or they already had some keys (but less than 12) in their inventory. It will not pickup more to put us over one stack.

Specific scenarios this fixes:

1. Act 2 scrolls will run out and not be re-purchased
2. Act 3 keys will run out and not be re-purchased

Interface change:

[elobo91]

Hello, could you add keys to item_pickup in shouldbepickedup . Keys drop often from chests and it prevent going to town for nothing while it can sustain with drops. You will need to check stack quantity on ground if it fits stack in inventory ( max 12) . Key drop can be 1-2-3-4 key stacks . We cant use .nip for that as it wouldnt respect max key count and make multiple stack. Buying at vendor when 1 key left( tp to town to refill) For scrolls vendor is totally fine. Pr look good otherwise thanks

[sorc653]

Hello, could you add keys to item_pickup in shouldbepickedup . Keys drop often from chests and it prevent going to town for nothing while it can sustain with drops. You will need to check stack quantity on ground if it fits stack in inventory ( max 12) . Key drop can be 1-2-3-4 key stacks . We cant use .nip for that as it wouldnt respect max key count and make multiple stack. Buying at vendor when 1 key left( tp to town to refill) For scrolls vendor is totally fine. Pr look good otherwise thanks

Change complete!

[sorc653]

Don't merge yet, going to have it only pick up keys if you are opening chests.

[sorc653]

Ready for merge!