Add java helpers a-la python helpers

Author: jgriffiths

src/swig_java/jni_extra.java_in

@@ -5,6 +5,34 @@
       return aes(jarg1, jarg2, jarg3, null);
   }
 
+  public final static String base58check_from_bytes(byte[] bytes) {
+      return base58_from_bytes(bytes, BASE58_FLAG_CHECKSUM);
+  }
+
+  private final static byte[] base58_to_bytes(String base58, long flags) {
+      final byte buf[] = new byte[base58_get_length(base58)];
+      final int len = base58_to_bytes(base58, flags, buf);
+      return trimBuffer(buf, len);
+  }
+
+  public final static byte[] base58_to_bytes(String base58) {
+      return base58_to_bytes(base58, 0);
+  }
+
+  public final static byte[] base58check_to_bytes(String base58) {
+      return base58_to_bytes(base58, BASE58_FLAG_CHECKSUM);
+  }
+
+  public final static Object bip32_pub_key_init(final int version, final int depth, final int childNum,
+                                         final byte[] chainCode, final byte[] pubKey) {
+      return Wally.bip32_key_init(version, depth, childNum, chainCode, pubKey, null, null, null);
+  }
+
+  public final static Object bip32_priv_key_init(final int version, final int depth, final int childNum,
+                                                 final byte[] chainCode, final byte[] privateKey) {
+      return Wally.bip32_key_init(version, depth, childNum, chainCode, null, privateKey, null, null);
+  }
+
   public final static byte[] bip32_key_get_chain_code(Object jarg1) {
       return bip32_key_get_chain_code(jarg1, null);
   }