Merge CommandService and ProcessService to CommonService

- Replace CommandService and ProcessService with CommonService: a service that offers our typical needs to work with settings, messages and permissions
- Remove validation methods from CommonService: inject ValidationService directly. Validation methods are not used very frequently and therefore don't belong in CommonService. Their presence was a relict from our architecture before injection was used.

src/main/java/fr/xephi/authme/service/CommonService.java

@@ -0,0 +1,110 @@
+package fr.xephi.authme.service;
+
+import com.github.authme.configme.properties.Property;
+import fr.xephi.authme.message.MessageKey;
+import fr.xephi.authme.message.Messages;
+import fr.xephi.authme.permission.AuthGroupHandler;
+import fr.xephi.authme.permission.AuthGroupType;
+import fr.xephi.authme.permission.PermissionNode;
+import fr.xephi.authme.permission.PermissionsManager;
+import fr.xephi.authme.settings.Settings;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+
+import javax.inject.Inject;
+
+/**
+ * Service for the most common operations regarding settings, messages and permissions.
+ */
+public class CommonService {
+
+    @Inject
+    private Settings settings;
+
+    @Inject
+    private Messages messages;
+
+    @Inject
+    private PermissionsManager permissionsManager;
+
+    @Inject
+    private AuthGroupHandler authGroupHandler;
+
+    CommonService() {
+    }
+
+    /**
+     * Retrieves a property's value.
+     *
+     * @param property the property to retrieve
+     * @param <T> the property type
+     * @return the property's value
+     */
+    public <T> T getProperty(Property<T> property) {
+        return settings.getProperty(property);
+    }
+
+    /**
+     * Sends a message to the command sender.
+     *
+     * @param sender the command sender
+     * @param key the message key
+     */
+    public void send(CommandSender sender, MessageKey key) {
+        messages.send(sender, key);
+    }
+
+    /**
+     * Sends a message to the command sender with the given replacements.
+     *
+     * @param sender the command sender
+     * @param key the message key
+     * @param replacements the replacements to apply to the message
+     */
+    public void send(CommandSender sender, MessageKey key, String... replacements) {
+        messages.send(sender, key, replacements);
+    }
+
+    /**
+     * Retrieves a message.
+     *
+     * @param key the key of the message
+     * @return the message, split by line
+     */
+    public String[] retrieveMessage(MessageKey key) {
+        return messages.retrieve(key);
+    }
+
+    /**
+     * Retrieves a message in one piece.
+     *
+     * @param key the key of the message
+     * @return the message
+     */
+    public String retrieveSingleMessage(MessageKey key) {
+        return messages.retrieveSingle(key);
+    }
+
+    /**
+     * Checks whether the player has the given permission.
+     *
+     * @param player the player
+     * @param node the permission node to check
+     * @return true if player has permission, false otherwise
+     */
+    public boolean hasPermission(Player player, PermissionNode node) {
+        return permissionsManager.hasPermission(player, node);
+    }
+
+    /**
+     * Sets the permission group of the given player.
+     *
+     * @param player the player to process
+     * @param group the group to add the player to
+     * @return true on success, false otherwise
+     */
+    public boolean setGroup(Player player, AuthGroupType group) {
+        return authGroupHandler.setGroup(player, group);
+    }
+
+}