Add liquidity from any asset on Balancer

[jmusighi]

Requested by Jeff Garzik (https://twitter.com/jgarzik):

"Feature request: Add Liquidity to any pool, with any asset on Balancer.

e.g. Acquire BAL/WETH LP tokens with WBTC. Needs no smart contract changes... Just a couple more front end swaps

In theory, yes, Zapper should do this; however, most aggregators only support this for whitelisted coins, leaving a large universe of NewCoins and NanoCoins out in the dust.

In practice,

1. Aggregators are dumb. 1inch completely fails to see my COIN1/COIN2 Balancer pool, because neither COIN1 nor COIN2 is a major liquidity coin. As a result, https://t.co/FbOIBXSk5y often gives a better price than aggregator.
2. Aggregators use whitelists. The "zapper can do it" thesis works today for (a) popular input coins and (b) popular Balancer pools. For NewCoins and NanoCoins, token holders must suffer through the whitelist process & wait.
3. Balancer approximates best price. Between the overall system design and DEX arb bots, you can generally get a very good price for your swap via https://t.co/FbOIBXSk5y Only professional traders will notice a difference.
4. Because of Add liquidity from any asset on Balancer #1, you might get best price.
5. Show off your awesome tech! 😀 This should be straightforward mashup of https://t.co/FbOIBXSk5y & https://t.co/xQ6F9ddE0Q
6. Saves gas ($$) and time for your users."