Replace side "Buy, Sell" with "BTO, STC, STO, BTC"

My algorithm _sometimes_ tries to sell a position twice, which results in in liquidation of my current position and then the filling of a short order. In a perfect world, our code is so tried and tested that this could never happen by mistake. But, as we know, we do not live in a perfect world and bugs occur, regressions occur, hiccups occur.

The accidental shorting of an equity due to two sell orders clearing is dangerous, unacceptable and yet, completely avoidable by a responsible API.

**Recommendation:**

**Please replace current "Buy, Sell" options with the following:**

**BTO** = Buy To Open
**STC** = Sell To Close
**STO** = Sell To Open
**BTC** = Buy To Close

This will ensure orders accepted by the API are accepted **as intended** by the developer and it will help protect your clients equity.