Subtract fee from amount

Fixes #2724 and #1570.

Adds the
automatically-subtract-the-fee-from-the-amount-and-send-whats-left
feature to the GUI and RPC (sendtoaddress,sendmany).

src/rpcclient.cpp

@@ -32,6 +32,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "getnetworkhashps", 0 },
     { "getnetworkhashps", 1 },
     { "sendtoaddress", 1 },
+    { "sendtoaddress", 4 },
     { "settxfee", 0 },
     { "getreceivedbyaddress", 1 },
     { "getreceivedbyaccount", 1 },
@@ -59,6 +60,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "listsinceblock", 2 },
     { "sendmany", 1 },
     { "sendmany", 2 },
+    { "sendmany", 4 },
     { "addmultisigaddress", 0 },
     { "addmultisigaddress", 1 },
     { "createmultisig", 0 },