slow start, increasing number of blocks worked on per thread, reusing ciphers for multiple consecutive blocks

main/crypto-api/src/main/java/org/cryptomator/crypto/exceptions/EncryptFailedException.java

@@ -3,6 +3,10 @@ package org.cryptomator.crypto.exceptions;
 public class EncryptFailedException extends CryptingException {
 	private static final long serialVersionUID = -3855673600374897828L;
 
+	public EncryptFailedException(Throwable t) {
+		super("Encryption failed.", t);
+	}
+
 	public EncryptFailedException(String msg) {
 		super(msg);
 	}