#1015 Implement lazy replace of tags for welcome message

- Check which tags are used when loading the welcome message and only apply their replacements afterwards
- Moves AuthMe#replaceAllInfo to a more appropriate place
- Avoid fetching data again for each line

src/main/java/fr/xephi/authme/util/lazytags/Tag.java

@@ -0,0 +1,53 @@
+package fr.xephi.authme.util.lazytags;
+
+import org.bukkit.entity.Player;
+
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+/**
+ * Represents a tag in a text that can be replaced with data (which may depend on the Player).
+ */
+public class Tag {
+
+    private final String name;
+    private final Function<Player, String> replacementFunction;
+
+    /**
+     * Constructor.
+     *
+     * @param name the tag (placeholder) that will be replaced
+     * @param replacementFunction the function producing the replacement
+     */
+    public Tag(String name, Function<Player, String> replacementFunction) {
+        this.name = name;
+        this.replacementFunction = replacementFunction;
+    }
+
+    /**
+     * Constructor.
+     *
+     * @param name the tag (placeholder) that will be replaced
+     * @param replacementFunction supplier providing the text to replace the tag with
+     */
+    public Tag(String name, Supplier<String> replacementFunction) {
+        this(name, p -> replacementFunction.get());
+    }
+
+    /**
+     * @return the tag
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * Returns the value to replace the tag with for the given player.
+     *
+     * @param player the player to evaluate the replacement for
+     * @return the replacement
+     */
+    public String getValue(Player player) {
+        return replacementFunction.apply(player);
+    }
+}