fix(trader): Ensure consolidation of only same-currency trades

Changes include:
* unbinding _private_, and pure methods from prototype of a `Trader` object:
  * `Trader.prototype._findExchange` => `findExchange`,
  * `Trader.prototype._findTicker` => `findTicker`,
  * `Trader.prototype._findTrader` => `findTrader`,
  * `Trader.prototype._findWallet` => `findWallet`.

* Some local variables renamed to improve readability:
  * `tradeRec` => `consolidatedTrade`
  * `tickerExchangeCode` => `tickerName`,
  * `tickerExchangeConfig` => `tickerConfig`,
  * `tradeExchangeCode` => `traderName`,
  * `tradeExchangeCode` => `traderConfig`,
  * `transferExchangeCode` => `walletName`,
  * `transferExchangeConfig` => `walletConfig`.

* Since addition is commutative and order of looping doesn't matter: `while (true)` loop changed to `for..in`,
* `consolidateOther` and `otherCurencies` are used to consolidate if other currencies occur in queue.

Good point, but I think it's wise to stay away from this in all cases because iterating over an array is generally expected to iterate in order, so always iterating in order makes the code clearer. It's also generally accepted as best practice in JavaScript.