New BSIP: Design a Primary market which can map the orders of the Gateway market

***Cause***
Inter-Blockchain technology still needs much time to research and develop, but we still need to design a market first for these functions or other.
BTS has so many gateway markets, but can't make a well depth and liquidity for each other and users.
The target audience was limited for the gateway market.

***GOAL***
Design a market first for these functions or other.
Solve the decentralized problem of gateway market, give the user more better trading experience, they don't need to face the poor depth and liquidity of the gateway market which they only know.
Give the gateway a more wider audience, increase the depth and liquidity.

***Precondition***
Multi-signature wallet;
Primary market;

***Scheme***
1. A multi-signature wallet(like BTC).
People deposit BTC to Gateway BTC wallet，Gateway BTC wallet transfer BTC to multi-signature BTC wallet, then the multi-signature wallet issue the Gateway.UIA.
Person deposit BTC to the multi-signature wallet directly, this multi-signature wallet will issue the multi-signature UIA in the Primary market.

2. The gateway want to access the Primary market or the Gateway market want to be mapped the orders by Primary market, the gateway must transfer all the BTC and issuer authority to the multi-signature wallet;

3. Design a Primary market: this market will map the orders of the Gateway market which have achieved the necessary condition 2.
The asset in this Primary market will have the same name, e.g. gdex.btc will be btc, open.btc will be btc.

In the Primary market:
Taker can fill the orders which were mapped to the Primary market; the real trade happend in the Gateway market.
Taker can fill the pending orders which were directly placed in the the Primary market; the real trade happend in the Primary market.
The orders which happend in the Gateway market directly will can't influence the maker in the Primary market;
The asset of the gateway which have achieved the necessary condition 2 can directly trad in Primary market;

***Problem***
The safe of multi-signature wallet;
Market fee problem;
The member of multi-signature wallet;
...

***Example***

The issue names no files, tests, or implementation entry points. Start by reviewing the proposed multi-signature wallet and Primary market scheme, then resolve the stated wallet safety, market fee, and membership questions. Done means an agreed, implementable design for mapping Gateway market orders.

Written by the indexing model from the issue text.