tiers wave reward section.
This commit introduces a new optional wave rewards section, `tiers`, which allows server owners to configure rewards that "upgrade" over time. This makes it possible to create reward configurations where (some of) the rewards don't stack as the waves progress, but instead change into different rewards. The most obvious use case is wanting to grant an armor set for beating a specific wave, but a _better_ set for beating a later wave, without granting both sets. Turns out this was a lot easier than I thought it would be. We didn't even need a rework of anything, and the Things API didn't even need to adapt in any way. As an added bonus, we managed to get the associated GitHub issue wrapped up before it turned 8 years old. Neat! Closes #346
MobArena 
MobArena is an arena-style minigame for Spigot-based Minecraft servers
Getting Started
If you don't want to compile the plugin yourself, grab a release artifact from one of these two sites:
The wiki here on Github should have all the information you need to get started using the plugin.
Getting Help
If you run into problems or need help with something, feel free to hop on the MobArena Discord server to have a chat: Instant Invite
Remember, though, that this communication channel is idle chat, which means you likely won't get a response immediately. It could take anything from a couple of seconds to a day, but your message will be seen.
Contributing
Found a bug, got a suggestion, or want to dig into the code base? There are many ways to contribute to the project!
Get started here: Contributing