extend ability system to support dynamic slot counts, add skill tree validation, new prerequisites API, and extended mod commands

src/main/java/net/fretux/skillengine/api/AbilityHandler.java

@@ -0,0 +1,9 @@
+package net.fretux.skillengine.api;
+
+import net.fretux.skillengine.skilltree.AbilityNode;
+import net.minecraft.server.level.ServerPlayer;
+
+@FunctionalInterface
+public interface AbilityHandler {
+    boolean execute(ServerPlayer player, AbilityNode ability);
+}