Merge #9333: Document CWalletTx::mapValue entries and remove erase of nonexistent "version" entry.

87ed396 [trivial] Add comment documenting bumpfee mapValues (Russell Yanofsky)
a1fe944 Remove reference to nonexistent "version" wallet transaction mapvalue field (Russell Yanofsky)
654e044 [trivial] Add comment documenting CWalletTx::mapValue (Russell Yanofsky)

Tree-SHA512: 1fd1860e345c59b13634db2007fff4ba30aaf1f177fdd765f47bf9257fac117cdcd5d491424416da304c08e85effbb27f3424f072f7c9587ef39cb98531b932a

src/wallet/wallet.h

@@ -256,6 +256,31 @@ private:
     const CWallet* pwallet;
 
 public:
+    /**
+     * Key/value map with information about the transaction.
+     *
+     * The following keys can be read and written through the map and are
+     * serialized in the wallet database:
+     *
+     *     "comment", "to"   - comment strings provided to sendtoaddress,
+     *                         sendfrom, sendmany wallet RPCs
+     *     "replaces_txid"   - txid (as HexStr) of transaction replaced by
+     *                         bumpfee on transaction created by bumpfee
+     *     "replaced_by_txid" - txid (as HexStr) of transaction created by
+     *                         bumpfee on transaction replaced by bumpfee
+     *     "from", "message" - obsolete fields that could be set in UI prior to
+     *                         2011 (removed in commit 4d9b223)
+     *
+     * The following keys are serialized in the wallet database, but shouldn't
+     * be read or written through the map (they will be temporarily added and
+     * removed from the map during serialization):
+     *
+     *     "fromaccount"     - serialized strFromAccount value
+     *     "n"               - serialized nOrderPos value
+     *     "timesmart"       - serialized nTimeSmart value
+     *     "spent"           - serialized vfSpent value that existed prior to
+     *                         2014 (removed in commit 93a18a3)
+     */
     mapValue_t mapValue;
     std::vector<std::pair<std::string, std::string> > vOrderForm;
     unsigned int fTimeReceivedIsTxTime;
@@ -369,7 +394,6 @@ public:
         }
 
         mapValue.erase("fromaccount");
-        mapValue.erase("version");
         mapValue.erase("spent");
         mapValue.erase("n");
         mapValue.erase("timesmart");