v0.18: Big changes to coins and items

# Removed auto-dropping coins, changed how items work

Coins and other items no longer automatically drop into the jar. Now things only go in the jar when you deliberately drop them in there.

The idea with this change is to make it a little more strategic about where and when you place things in the jar. The following changes (and more in the future) mean the contents of your jar now matter quite a bit more than before. So maintaining space in your jar will be an important consideration.

1. Upgrades that cost items (like lemon slices, bottle caps, etc.) are now unlocked based on the number _presently in the jar_. End-game upgrades will require a large number of items, so you'll have to be strategic about filling up the jar to afford them.

2. Items in the jar grant a bonus to ventures' incomes. Example: 12 lemon slices give a total 120% bonus to the lemonade stand.

3. There is an upgrade for each type of item that makes them affect the point multiplier as well. Example: with the lemon slice upgrade, 12 lemon slices in the jar will also grant 1.2x to your point multiplier.

4. Ventures generate items over time and these items will appear in your inventory. Select an item in your inventory to begin dropping that type of item (instead of coins). Click again to go back to coins.

This also means there is no need to enable/disable ventures, so these buttons were removed.

5. Items in your inventory are capped, starting at 20 each. This number can be upgraded.

# Other updates

## Poker

- Added ability to sort by suit and rank to make it easier to find the cards you want to turn in.

- Fixed an issue where having lots of cards caused them to run off the side of the screen; you can now scroll through the cards by clicking and dragging left/right.

## Coins

- Coin Base Value upgrade now doubles each time i.e. 2->4->8->16

- Coin Drop Cooldown is now based on how many coins you've dropped

- Changed the way coins look. Coins with large values are now formatted e.g. 1024 appears as "1K"