Add public field 'memo' to JSOutput to enable creation of notes with custom memos.

src/zcash/JoinSplit.cpp

@@ -214,11 +214,8 @@ public:
             ZCNoteEncryption encryptor(h_sig);
 
             for (size_t i = 0; i < NumOutputs; i++) {
-                // TODO: expose memo in the public interface
-                // 0xF6 is invalid UTF8 as per spec
-                boost::array<unsigned char, ZC_MEMO_SIZE> memo = {{0xF6}};
 
-                NotePlaintext pt(out_notes[i], memo);
+                NotePlaintext pt(out_notes[i], outputs[i].memo);
 
                 out_ciphertexts[i] = pt.encrypt(encryptor, outputs[i].addr.pk_enc);
             }

src/zcash/JoinSplit.hpp

@@ -35,6 +35,7 @@ class JSOutput {
 public:
     PaymentAddress addr;
     uint64_t value;
+    boost::array<unsigned char, ZC_MEMO_SIZE> memo = {{0xF6}};  // 0xF6 is invalid UTF8 as per spec, rest of array is 0x00
 
     JSOutput();
     JSOutput(PaymentAddress addr, uint64_t value) : addr(addr), value(value) { }