[fix] Freecam chunk rendering (#1644)

* [fix] Appropriately modify `renderChunksMany` when toggling Freecam

To optimise chunk rendering, minecraft tries to omit (normally) invisible chunks from chunk rendering. However, when the player's head is in an opaque block AND the classic 'block in head' overlay is not drawn, the player should see a sort of x-ray like view of the world. This happens in e.g. spectator mode. The `renderChunksMany` field in Minecraft also controls this behaviour, allowing modders to turn off the optimisation.

* [cleanup] Extract Freecam camera entity ID to constant field

src/main/java/me/zeroeightsix/kami/module/modules/player/Freecam.kt

@@ -41,19 +41,26 @@ object Freecam : Module() {
     var cameraGuy: EntityPlayer? = null; private set
     var resetInput = false
 
+    private const val ENTITY_ID = -6969420
+
     override fun onDisable() {
+        mc.renderChunksMany = true
+
         if (mc.player == null) return
-        mc.world.removeEntityFromWorld(-6969420)
+        mc.world.removeEntityFromWorld(ENTITY_ID)
         mc.setRenderViewEntity(mc.player)
         cameraGuy = null
         if (prevThirdPersonViewSetting != -1) mc.gameSettings.thirdPersonView = prevThirdPersonViewSetting
     }
 
+    override fun onEnable() {
+        mc.renderChunksMany = false
+    }
+
     init {
         listener<ConnectionEvent.Disconnect> {
             prevThirdPersonViewSetting = -1
             cameraGuy = null
-            mc.renderChunksMany = true
             if (disableOnDisconnect.value) disable()
         }
 
@@ -95,7 +102,7 @@ object Freecam : Module() {
         // Create a cloned player
         cameraGuy = FakeCamera(mc.player).also {
             // Add it to the world
-            mc.world.addEntityToWorld(-6969420, it)
+            mc.world.addEntityToWorld(ENTITY_ID, it)
 
             // Set the render view entity to our camera guy
             mc.setRenderViewEntity(it)