[Loopring3] refactor deployment process to support upgradability

[dong77]

1. ABI files will be generated automatically before tests run, so they are deleted from git.
2. LoopringRegistry now maintains the ids of all exchanges (cross-version) and will burn LRC when an exchange is created, LoopringV3.sol only maintains exchanges based on LoopringV3.

[Brechtpd]

@Brechtpd @kongliangzhong it turns out I have to change some internal functions inside Exchange**.sol libraries to public in order not to inline those functions into ExchangeV3Deployer to reduce the size of ExchangeV3Deployer.

Another way to lower the deployment cost is to lower the number of 'runs' in the optimizer here (delete all build files of contracts because truffle isn't always smart enough to recompile the contracts). This normally also increases the gas cost of actually using the functions, but not making functions internal also increases the gas cost, so we'll have to experiment a bit to find the best parameters. But we can do that later.

[dong77]

@Brechtpd @kongliangzhong it turns out I have to change some internal functions inside Exchange**.sol libraries to public in order not to inline those functions into ExchangeV3Deployer to reduce the size of ExchangeV3Deployer.

Another way to lower the deployment cost is to lower the number of 'runs' in the optimizer here (delete all build files of contracts because truffle isn't always smart enough to recompile the contracts). This normally also increases the gas cost of actually using the functions, but not making functions internal also increases the gas cost, so we'll have to experiment a bit to find the best parameters. But we can do that later.

Good to know. But now we are good to go. Not sure what will happen after we introduce more features.

[dong77]

@kongliangzhong can you review the IProtocolRegistry and ProtocolRegistry for me?