Kotlin inaccessable field support

[GregHib]

Artemis fails to access @EntityId fields via reflection ReflectionException: Illegal access to field, because of the way Kotlin generates getters and setters which leaves the field itself private. See IntFieldMutator.

[HybridEidolon]

A workaround is to add the @JvmField annotation to the property, but I am not certain that will work well if you have explicit get/set definitions.

Not having any experience with artemis, it seems that com.artemis.utils.reflect.Field should have an abstraction over getter/setter method pairs in addition to delegating to the java.lang.reflect.Field in order to support this use case, and using those if they're present over the field itself. This would make all mutators work on JVM in the general case.

[DaanVanYperen]

Added a wiki page to help out Kotlin users.
https://github.com/junkdog/artemis-odb/wiki/Kotlin

The @JvmField workaround should suffice for now, i'm putting this in the freezer as a nice-to-have. If we ever find the time @HybridEidolon solution would be the way to go.