Resolve "Init block configuration depends on where it is declared"

Closes #59 (closed)

This is a bigger rework of some internals and the feature api.

Old syntax:

class Ark(vararg arguments: String) : Arkenv() {
    init {
        install(ProfileFeature())
        parse(arguments.toList().toTypedArray())
    }

    val port: Int by argument("--port")
    val name: String by argument("--name")
}

New config syntax:

class Ark : Arkenv("Test", {
    install(ProfileFeature())
}) {
    val port: Int by argument("--port")
    val name: String by argument("--name")
}