Merge pull request #7 from jottinger/master

Adding jacoco verifications for complexity and coverage

Adding jacoco for coverage reports

Adding tests for addEdge

Updating gradle

Updating to use current gradle and JDK

Update README.md

Add files via upload

Merge pull request #5 from carldea/master

Revert back to Java 8 as the target release.

Added other versions of Java

Test on other OSes

Build project using CI and GitHub Actions

Update ci.yml

Use GitHub Actions to test project.