Added /sell multipliers

[justinmtech]

Information

This PR closes #3934

Details

Proposed feature:

Sell Command multipliers! The idea is for servers to be able to control how much players can /sell their items for based on permissions. If a player has the permission "essentials.sell.multiplier.2", their items will sell with double worth. It works with decimals as well, and even values less than 1.
#3934

Environments tested:

OS: Windows 10

Java version: OpenJDK 17.0.1

• Most recent Paper version (1.18.1, Permission for modified spawner? #153)
• CraftBukkit/Spigot/Paper 1.12.2
• CraftBukkit 1.8.8

Demonstration:

Screenshot: https://i.imgur.com/ju0jMUy.png
Here I give myself a diamond and sell it with no permissions (as op), then I give myself the "essentials.sell.multiplier.2" permission and as you can see, my sell price is double.
Plugin Download: https://www.dropbox.com/s/2qwzn2st8ln5i1q/EssentialsX-2.19.3-dev%2B6-739600e-sell-multipliers.jar?dl=0

[pop4959]

I think a better implementation of this would be like that suggested by Chew in the linked issue. Allow defining multipliers in the configuration as with home permissions, to not have to iterate everything and parse.

[justinmtech]

I think a better implementation of this would be like that suggested by Chew in the linked issue. Allow defining multipliers in the configuration as with home permissions, to not have to iterate everything and parse.

You're right. I will try to re-work this soon when I have time.