Improving Gateway/Bridge Documentation and Codebase

The current system used for gateway/bridge access and communication is now a few years old and was introduced with the addition of Openledger.

The lack of documentation and knowledge of the workings of this has greatly limited the introduction of new gateways to the platform. Some work has been made to enhance the quality, but it still lacks some documents and has some confusing questions.

As a start, we should continue to improve the documentation, and perfect the current codebase.

# Major Tasks
- [ ] Enhance codebase (~10-15 hours) - https://github.com/bitshares/bitshares-ui/issues/2010
- [ ] Finish documentation of the Gateway and Bridge functions (~5 hours) - https://github.com/bitshares/bitshares-ui/issues/2011
- [ ] Swagger documentation (~5 hours) - https://github.com/bitshares/bitshares-ui/issues/2011

# Larger Tasks
- [ ] Removal of Legacy Gateway/Bridge - https://github.com/bitshares/bitshares-ui/issues/2249
- [ ] Streamline updateGatewayBackers usage - #2484

# Minor Tasks
- [ ] Handle long reponses for external address queries - #1428
- [ ] Exchange Gateway Deposit Replacement - #2144
- [ ] Warning text when you click Deposit/Withdraw for the first time - #821
- [ ] Add 'State of the Gateways' feed in News section - #2445
- [ ] Integration Testing - Quick Deposit Button Missing - #2180
- [x] Withdraw Modal Enhancements #2522
- [x] Legacy Despot/Withdraw Issues - https://github.com/bitshares/bitshares-ui/issues/2325
- [x] Gateway Modal ANT Implementation - https://github.com/bitshares/bitshares-ui/issues/1872
- [x] New Deposit / Withdraw modal u/s - #2446
- [x] Deposit operation - inoperable - #2469
- [x] Portfolio Deposit/Witdhraw/Buy Icons doesn't render on logged out Cloud Accounts - #2487

# Sub-Tasks
- [x] New Gateway API Drafting - #2477

### Update 2018-10-02
Walking through the code of the Gateway/Bridge system, a number of difficulties where found and the code is a jumble. There are a number of enhancements that can be made to improve this system. Some was made as part of #1872 . The hours have been updated to ~20-25 hours for this.

### Update 2019-02-14
Task raised to Epic to track all issues related to Deposits and Withdrawls on Gateways and Bridges

Start by reviewing the linked subtasks #2010 and #2011, which cover codebase improvements, Gateway and Bridge documentation, and Swagger documentation. Use the listed gateway-related issues and the 2019 epic update to establish scope; the work is done when the missing documentation and identified codebase problems are addressed.

Written by the indexing model from the issue text.