List the available operations and arg types in the interactive invoke menu when using contract download

[edgedlt]

Third time lucky? Moved neo-project/neo-visual-tracker#167:

I really like having the available functions and parameter types for deployed contracts that I've compiled locally. Though my main use for contract download will be for testing contracts that call the downloaded contracts, being able to quickly invoke them with the GUI is useful at times too.

I assume this data is populated using the manifest, one extra call to getcontractstate during contract download should be enough to fetch the ABI.

Actually I noticed that I don't have this info for native contracts either, though I'm fairly certain they used to be there. Maybe a bug?