bump version and update civgradle

Bump version to 2.1.0

Update build.gradle.kts

Update version

version

Update dependency names

Update to spigot 1.12

Merge pull request CivClassic#18 from iykHvfIvfR/pr1

Clean up the code

Refactored and more efficient distance / world checking, plus working…

… distance-based coloring.

Making join announce a configuration option.

Conflicts:
	pom.xml