Bitshares-core: Implement FIX 4.4

[abitmore]

FIX 4.4 is mentioned in Binance Dexathon: https://medium.com/binanceexchange/binance-dexathon-845dc0cbfffe. The specification is here: https://www.fixtrading.org/standards/fix-4-4/

[jmjatlanta]

I see FIX/FAST implementations as a good wins for Bitshares. IMHO: it makes the DEX "industry ready".

FIX:
One implementation option would be a cli_wallet replacement. The middle "client" has the application connection on the back end, with FIX on the front end. Advantages: Easy to implement, and doesn't affect existing code. Disadvantage: would add another translation step to the middle.

A deeper implementation would make FIX more "native" to the api node, but keys/authentication would require some forethought and work.

FAST:
Providing book and price feeds using FAST would almost certainly lighten network congestion, and therefore would allow more concurrent connections. I'm not as familiar with the Bitshares implementation of the book and price feeds, so I'm not yet comfortable describing possible implementations.

[clockworkgr]

Good thing is there are many Open Source implementations of both available (some in C++) as well as related projects that can be leveraged to achieve this.

https://github.com/objectcomputing/quickfast

https://github.com/objectcomputing/mFAST

https://github.com/fix8/fix8

https://github.com/libtrading/libtrading

https://github.com/jamesdbrock/hffix

[oxarbitrage]

please note open source != mit for a possible usage into the core.

[clockworkgr]

Provided mostly for reference. Didnt check licenses.

What other licenses are "compatible" to MIT? I see fix8 is LGPL which should be fine. Others?