Fix RPC output for trade matches.
Fix RPC output for trade matches.

Notes:
The following shows a sell for 2000 Indiv for 1.0 Div.

  The original offer
     "matches" : [
         {
             "txid" : "da18e6d80b8340d8f872ff14ff002ab645552760d12060e7e50d62d6a20539ee",
             "block" : 126,
             "address" : "mpwugZU3hfVkQzBumVNAkqB3cJKkpNxotJ",
             "amountsold" : "1999",
             "amountreceived" : "1.00000000",
             "tradingfee" : "0.00000001"
         }
     ],
     "block" : 125,

  The new offer (the liquidity taker):
     "matches" : [
         {
             "txid" : "4812b0389017b479d3fa8a0674d5b7403d07cd6a0d11d4133eb281816a91d7a8",
             "block" : 126,
             "address" : "mpwugZU3hfVkQzBumVNAkqB3cJKkpNxotJ",
             "amountsold" : "1.00000000",
             "amountreceived" : "1999"
         }
     ],
     "block" : 126,

This has the following bugs:
   * Trading fee incorrectly appears in original offer matches when they did not pay any fee
   * Trading fee does not appear in liquidity taking offer matches when they did pay a fee
   * Trading fee shows incorrect divisibility
   * Amount sold attribute in the original offers matches array shows 1999 sold, when in fact 2000 were sold

This commit squashes these issues with an update to getMatchingTrades.  Afterwards the same test gives results:

  The original offer:
     "matches" : [
         {
             "txid" : "612baeb13daf43fa3e9c5e46b736f7b07d1d395c3b2a578befa4060d037c2594",
             "block" : 126,
             "address" : "mta18HMfntLhXHWezu4Nuc4Wzsxw2aDxKv",
             "amountsold" : "2000",
             "amountreceived" : "1.00000000",
             "tradingfee" : "0.00000000"
         }
     ],
     "block" : 125,

The new offer (the liquidity taker):
     "matches" : [
         {
             "txid" : "0214cf43bed73cb6432f9ecc103421ed33ec1c49d2005e01d180b38811f6a87f",
             "block" : 126,
             "address" : "mta18HMfntLhXHWezu4Nuc4Wzsxw2aDxKv",
             "amountsold" : "1.00000000",
             "amountreceived" : "1999",
             "tradingfee" : "1"
         }
     ],
     "block" : 126,

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