ADJUSTED_LAST is missing from Historical Data Types (whatToShow)

[crwpenn]

The TWS API includes ADJUSTED_LAST as an option for historical data that returns prices adjusted for both splits and dividends, but that choice is missing from market_data::historical::WhatToShow.

It's also missing from the current version of the Interactive Brokers API documentation here. However, it does appear in the older documentation available here. The API does still work correctly with ADJUSTED_LAST, so this seems to be a deficiency of the current documentation rather than an intended change to the API.

I've created a PR to add AdjustedLast to market_data::historical::WhatToShow.