Add @LinkedTimer

A method of a linked class annotated with @LinkedTimer(delay, period) is run
repeatedly by the linker, on Spigot and Velocity. The method must not have
parameters, its return value is ignored. It is called through a MethodHandle
bound once when linking instead of reflection; LambdaMetafactory cannot be used
as the linker and the linked classes are in different class loaders.

The unit defaults to ticks and can be set to milliseconds up to hours; the
Unit enum converts it to ticks for Spigot and to a TimeUnit for Velocity.
HullHiderCommand uses it for its tick task.

BauSystem/BauSystem_Main/src/de/steamwar/bausystem/features/hullhider/HullHiderCommand.java

@@ -32,6 +32,7 @@ import de.steamwar.hullhider.HullRegion;
 import de.steamwar.hullhider.Viewers;
 import de.steamwar.linkage.Linked;
 import de.steamwar.linkage.LinkedInstance;
+import de.steamwar.linkage.LinkedTimer;
 import de.steamwar.techhider.ObfuscationConfig;
 import net.md_5.bungee.api.ChatMessageType;
 import org.bukkit.Bukkit;
@@ -55,8 +56,6 @@ public class HullHiderCommand extends SWCommand implements Listener {
 
     public HullHiderCommand() {
         super("hullhider");
-
-        Bukkit.getScheduler().runTaskTimer(BauSystem.getInstance(), this::onTick, 1, 1);
     }
 
     @Linked
@@ -140,6 +139,7 @@ public class HullHiderCommand extends SWCommand implements Listener {
         });
     }
 
+    @LinkedTimer(delay = 1, period = 1)
     private void onTick() {
         if (hidden.isEmpty()) return;