feat: call trace tree

[DanielSchiavini]

• implements #81

What I did

Allow users to generate a call tree of the last message call

How I did it

• Add call_trace method to the base EVM contract
• Allow trace to be printed or exported to HTML
• Fixed a bug in the ABI parser
• Test the interaction between ABI and Vyper contracts

How to verify it

• Tests are included

Description for the changelog

• Allow users to generate a call tree of the last message call

Cute Animal Picture

[charles-cooper]

can we split the etherscan caching into its own PR?

[DanielSchiavini]

@charles-cooper the trace is pretty unusable without the caching because it's so slow. I can split it though.