Increase encryption key size for Spigot protocol

1024 bits are very weak keys. This size equals vanillas implementation.
Therefore, 2048 goes out of spec, but works and requires only minimal
additional performance for improved security.

The consequence will be during the login and playing in onlinemode.
First for authenticating and second for the encryption of all following
packets.

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/listener/protocollib/EncryptionUtil.java

@@ -70,7 +70,7 @@ final class EncryptionUtil {
  public static final int VERIFY_TOKEN_LENGTH = 4;
  public static final String KEY_PAIR_ALGORITHM = "RSA";
 
- private static final int RSA_LENGTH = 1_024;
+ private static final int RSA_LENGTH = 2_048;
 
  private static final PublicKey MOJANG_SESSION_KEY;
  private static final int LINE_LENGTH = 76;