Allow @Polymorphic and @Priority on types, add value to @Polymorphic

This is the first step for listener level handler properties.

To allow a handler inside a polymorphic listener to be non-polymorphic,
the @Polymorphic annotation now has a boolean value that defaults to
true. In that case, it can be explicitly set to false to override the
listener-level default.

event-bus-core/src/main/java/dev/kske/eventbus/core/Polymorphic.java

@@ -1,6 +1,6 @@
 package dev.kske.eventbus.core;
 
-import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.*;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
 import java.lang.annotation.*;
@@ -8,6 +8,9 @@ import java.lang.annotation.*;
 /**
  * Allows an event handler to receive events that are subtypes of the declared event type.
  * <p>
+ * When used on a type, the value applies to all event handlers declared within that type that don't
+ * define a value on their own.
+ * <p>
  * This is useful when defining an event handler for an interface or an abstract class.
  *
  * @author Kai S. K. Engelbart
@@ -16,5 +19,12 @@ import java.lang.annotation.*;
  */
 @Documented
 @Retention(RUNTIME)
-@Target(METHOD)
+@Target({ METHOD, TYPE })
-public @interface Polymorphic {}
+public @interface Polymorphic {
+
+	/**
+	 * @return whether the event handler is polymorphic
+	 * @since 1.1.0
+	 */
+	boolean value() default true;
+}

event-bus-core/src/main/java/dev/kske/eventbus/core/Priority.java

@@ -1,6 +1,6 @@
 package dev.kske.eventbus.core;
 
-import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.*;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
 import java.lang.annotation.*;
@@ -9,6 +9,9 @@ import java.lang.annotation.*;
  * Defines the priority of an event handler. Handlers are executed in descending order of their
  * priority.
  * <p>
+ * When used on a type, the value applies to all event handlers declared within that type that don't
+ * define a value on their own.
+ * <p>
  * Handlers without this annotation have the default priority of 100.
  * <p>
  * The execution order of handlers with the same priority is undefined.
@@ -19,7 +22,7 @@ import java.lang.annotation.*;
  */
 @Documented
 @Retention(RUNTIME)
-@Target(METHOD)
+@Target({ METHOD, TYPE })
 public @interface Priority {
 
 	/**