Put McMMOPlayer to use where it made sense

It's basically a wrapper for anything related to players, as a
consequence Users.getProfile() is now depreciated.
Also removed SkillTools.xpProcessing() because of some redundancy with
McMMOPlayer.addXp().
+ some cleanup for consistency sake.

src/main/java/com/gmail/nossr50/util/Users.java

@@ -87,6 +87,7 @@ public final class Users {
      * @param player The player whose profile to retrieve
      * @return the player's profile
      */
+    @Deprecated
     public static PlayerProfile getProfile(OfflinePlayer player) {
         return getProfile(player.getName());
     }
@@ -97,6 +98,7 @@ public final class Users {
      * @param playerName The name of the player whose profile to retrieve
      * @return the player's profile
      */
+    @Deprecated
     public static PlayerProfile getProfile(String playerName) {
         McMMOPlayer mcmmoPlayer = players.get(playerName);