Add Shortened-Day Trade Schedule Awareness

[maxholloway]

Add Shortened-Day Trade Schedule Awareness

Summary

We do not currently take shortened days into account. More specifically, we allow a fixed amount of time for computation "within the same trading interval". For example, if the changes suggested in this issue are used, we will use the strat.options.tradinginterval (i.e. the tradinginterval argument specified in StrategyOptions) to determine how long we can place/fill orders for a particular bar. Since this is a fixed number, it does not take into account shortened days.

Solution

Solving this would involve at least the following steps:

1. Specifying a particular trading calendar.
2. Implementing logic to use that trading calendar (likely by generating a callable tradinginterval(today::Dates.Dates)).
3. Replacing the current logic of checking the tradinginterval static value with logic to check tradinginterval(today) for this while loop.