Cannot add or set scores of offline or "fake" players

The scoreboard subcommands "players set" and "players add" no longer support players who are not online. This results in many quirks, notably including:

• When the "*" wildcard is used, it will attempt to execute the command on all tracked players, but will fail for players who are offline.

• "Fake" players can no longer be manipulated. Fake players are a feature supported by Searge of Mojang, as seen when the #HiddenFakeName feature was added (names preceded with a # are not rendered in the sidebar).

In any case, if a player is not online, attempting to manipulate their score yields the message "That entity cannot be found."

Steps to Reproduce:

1. Create a new scoreboard objective,

   scoreboard objectives create Test dummy Test

2. Give yourself and another player scores in this objective,

   scoreboard players set <name> Test 100

3. Have the other player log off

4. Attempt to modify their score,

   scoreboard players set <name> Test 200

5. Observe that it fails: "That entity cannot be found."

6. Attempt to modify everybody's scores,

   scoreboard players set * Test 300

7. Observe that you receive two messages: one for your score (successfully changed), and one of failure (for the player who is not online)

8. Attempt to track a fake player, using a feature added in a previous snapshot,

   scoreboard players set #FakePlayer Test 500

9. Observe that it fails: "That entity cannot be found."

In previous versions, none of these commands would have failed.