Simple Order-Sends-Order (OSO) for market making

[abitmore]

User Story

As a market maker I'd like a simple OSO feature.

• A market maker places an order to buy asset A with asset B at price X, when the order gets filled, the system automatically places another order to sell A for B at higher price. When the new order gets filled, the system places another buy order at lower price. And again, and again, until the user cancels it.

Client software can place such orders in batches for grid trading strategies. When the orders are in place, no more maintenance is required.

Note: other OSO or OCO features are possible too, but this is the least risky one.

Impacts
Describe which portion(s) of BitShares Core may be impacted by your request. Please tick at least one box.

• API (the application programming interface)
• Build (the build process or something prior to compiled code)
• CLI (the command line wallet)
• Deployment (the deployment process after building such as Docker, Travis, etc.)
• DEX (the Decentralized EXchange, market engine, etc.)
• P2P (the peer-to-peer network for transaction/block propagation)
• Performance (system or user efficiency, etc.)
• Protocol (the blockchain logic, consensus, validation, etc.)
• Security (the security of system or user data, etc.)
• UX (the User Experience)
• Other (please add below)

Additional Context (optional)

• New BSIP: Conditional order - stop-limit, OSO, etc. bsips#126
• New BSIP: Leverage Same Capital to Place Order Across Multiple Trading Pairs to Increase Market Depth bsips#227

CORE TEAM TASK LIST

• Evaluate / Prioritize Feature Request
• Refine User Stories / Requirements
• Define Test Cases
• Design / Develop Solution
• Perform QA/Testing
• Update Documentation

[abitmore]

Done via #2749.