Support for lower Java versions

Hi!

Would it be possible to support lower Java versions, as Java 14 is not widely adapted? (there's only 8 and 11 in the official CentOS repos - the distro I run on my server)

(btw I didn't even know 14 existed before researching java class versions - I'm not a Java dev)

Oh, it would be also a good idea to mention it in the README :)

My OS: CentOS 8 (virtualized)

Using: java-11-openjdk.x86_64 (OpenJDK Runtime Environment 11) from the official CentOS repos

The error:

Could not load 'plugins/firstlight-1.1.1.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: com/natoboram/spigot/firstlight/FirstLight has been compiled by a more recent version of the Java Runtime (class file version 58.0), this version of the Java Runtime only recognizes class file versions up to 55.0

Thanks!

Edit: formatting

Edited Jun 15, 2020 by Jakub Smetana