Allows parameterized tests to use Item, Npc, and Object definitions
as @ArgumentSources.
This commit also adds support for using @ItemDefinitions etc on
properties as well as functions.
Updates the testing infrastructure to use the latest relesae of junit and
leverages the new extension mechanism to create an easy to use testing
framework. Also adds additional test coverage for several plugins.
Removes the dependency on legacy script compilation and now relies on script
discovery. In addition, the Gradle build scripts were refactored and updated
to be compatible with Gradle 5.0 and make use of the new java-library
configurations.
Major-