implement base-engine items

[eyedine2]

(both base-engine and mod items being loaded at the same time, the Bisicle overrides its default text.)

What this does:

• Implements some of the consumables from Undertale into the base version of the engine (it's a small amount, I need to do more later)
• Gives these items unique use text from the original game (Monster Candy was missing this in the world example mod). This does completely override their use functions, which may be completely unnecessary. It's a rough addition for now. (fixed by putting the final dialogue text into its own function that can be overwritten)
• Adds their text to the main localization files (and placeholder names for Serious Mode). English only unfortunately.
• adds a new tryRequire function to Utils, which tries to get module info from a mod and then the base engine if it fails
• Amends the Example world mod's save system to use this feature
• Messes around with the shop in the Example world mod a little.

Note:

As I said, item use being overridden is not ideal. Items should support comments on their own and be able to change the dialogue text without going into the use function. Maybe a getUseComment function? (again, fixed)

These were not rigorously tested, I do not know if they work in every situation. I am not a good coder, I may have missed some things. But overall I think it's a good step towards adding boilerplate items people may be wanting to use a lot.

[eyedine2]

converting this to a draft because it needs more work.