Support for system.multicall

[mgrrx]

The stdlib xmlrpc library has support for system.multicall. It would be nice to have the same feature in this library.

[mgrrx]

I’d be happy to work on this and provide a PR if there’s a chance to get this merged ;)

[mosquito]

Could you do it. I guess. :-)

[mosquito]

I already did this once for aiohttp-jsonrpc here, I think this simple approach could be useful to you.