Starting to stub out high-low strategy
 * Added expiry checking in StubBroker
Using standard deviations on daily highs to determine order signal and takeProfits
Refactored Pair object and added minimum balance in breakout strategy
Myriad bug fixes
 * Added more diagnostics
 * Refactored so that `units` refer to the counter currency
 * Cleanup
Starting to calculate a confidence factor to determine how many units are ordered, where the takeProfit is placed
Tweaking confidence factor in BreakoutStrategy
 * Reduced number of minutes in 'orders per minute' diagnostic to account for non-trading time