Move Eventhandling around.

I still want to use fabric still "array backed" events, but these here are just a bit easier to use from kotlin.

src/main/kotlin/moe/nea/notenoughupdates/features/NEUFeature.kt

@@ -0,0 +1,16 @@
+package moe.nea.notenoughupdates.features
+
+interface NEUFeature {
+    val name: String
+    val identifier: String
+    val defaultEnabled: Boolean
+        get() = true
+    var isEnabled: Boolean
+        get() = FeatureManager.isEnabled(identifier) ?: defaultEnabled
+        set(value) {
+            FeatureManager.setEnabled(identifier, value)
+        }
+
+    fun onLoad()
+
+}