Make mekanism energy conversion update

src/main/kotlin/ru/dbotthepony/mc/otm/compat/mekanism/Power.kt

@@ -17,28 +17,54 @@ import java.util.WeakHashMap
 
 private val LOGGER = LogManager.getLogger()
 
-// TODO: those are cached indefinitely, when, in fact, they can easily change
+private class LazyCache<O, T>(private val provider: () -> O, private val computer: (O) -> T) : Lazy<T> {
+	private var cache: T? = null
+	private var observed: O? = null
 
-private val mekanism2MtJ by lazy {
+	override fun isInitialized(): Boolean {
+		return cache != null
+	}
+
+	override val value: T get() {
+		if (cache == null || observed == null || observed != provider.invoke()) {
+			observed = provider.invoke()
+			cache = computer.invoke(observed ?: throw ConcurrentModificationException())
+		}
+
+		return cache ?: throw ConcurrentModificationException()
+	}
+}
+
+private class DoubleLazy<T>(onion: () -> Lazy<T>) : Lazy<T> {
+	private val onion = lazy(onion)
+	override val value: T
+		get() = onion.value.value
+
+	override fun isInitialized(): Boolean {
+		return onion.isInitialized() && onion.value.isInitialized()
+	}
+}
+
+private val mekanism2MtJ by DoubleLazy lazy@{
 	try {
 		val conf = MekanismConfig.general
-		return@lazy ImpreciseFraction.ONE / conf.forgeConversionRate.get().toImpreciseFraction()
+		return@lazy LazyCache(conf.forgeConversionRate::get) { ImpreciseFraction.ONE / it.toImpreciseFraction() }
 	} catch(err: Throwable) {
 		LOGGER.error("Unable to get Forge Energy to Mekanism Joules's conversion rate! Expect issues", err)
 	}
 
-	return@lazy ImpreciseFraction.ONE
+	return@lazy lazyOf(ImpreciseFraction.ONE)
 }
 
-private val mtj2Mekanism by lazy {
+private val mtj2Mekanism by DoubleLazy lazy@{
 	try {
 		val conf = MekanismConfig.general
-		return@lazy conf.forgeConversionRate.get().toImpreciseFraction()
+		return@lazy LazyCache(conf.forgeConversionRate::get) { it.toImpreciseFraction() }
 	} catch(err: Throwable) {
 		LOGGER.error("Unable to get Mekanism Joules's to Forge Energy conversion rate! Expect issues", err)
 	}
 
-	return@lazy ImpreciseFraction.ONE
+	return@lazy lazyOf(ImpreciseFraction.ONE)
 }
 
 class Mekanism2MatteryEnergyWrapper(private val power: IStrictEnergyHandler) : IMatteryEnergyStorage {