support US

[eddieran]

support binance.us

[xyq-c-cpp]

I don't think this modification is necessary to support it. Just set the value of BaseAPIMainURL or BaseWsMainURL before creating the client. Except in the options module where the associated values are not publicly available, if options support is also required, the associated values can be modified to be publicly visible. @eddieran

[eddieran]

I modified it this way with reference to the current support for testnet's domain.

// UseTestnet switch all the API endpoints from production to the testnet
var UseTestnet = false

[xyq-c-cpp]

@eddieran Take a look at those comments.