Staggered Orders Visualisation

[PermieBTS]

Relevent: #604

[Jackodb]

Updates on the visualisation part using dash/plotly can be found here: https://github.com/Jackodb/Visualization

[bitphage]

Required changes on strategy side (saved from telegram discussion):

• when initializing SO orders, save them to database
• if worker name is changed, that db is updated as well

[bitphage]

@Jackodb to retrieve worker orders several ways could be used:

1. call Account.openorders, then filter orders by it's market to match worker's market
2. call BitsharesOrderEngine property own_orders. It basically does exact thing as 1.

[Jackodb]

What if there are two workers on the same market @bitfag ?

[bitphage]

Same market with same account across multiple workers is not a valid situation, a check to prevent it will be added.