feat: flatten contracts

[iamdefinitelyahuman]

What I did

Add functionality for flattening a contract.

[fubuloubu]

Suggested change

	flattened_source = f"pragma solidity {version};{flattened_source}\n\n{source}\n"
	flattened_source = f"pragma solidity {version};\n\n{flattened_source}\n\n{source}\n"

[iamdefinitelyahuman]

It's handled in line 144

[Macarse]

This can be tested without deploying a new version.
Open a brownie terminal and use the contract like this:

for name in my_contract._build["dependencies"]:
  build_json = my_contract._project._build.get(name)
  offset = slice(*build_json["offset"])
  source = build_json["source"][offset]
  flattened_source = f"{flattened_source}\n\n{source}"

build_json = my_contract._build
version = build_json["compiler"]["version"]
offset = slice(*build_json["offset"])
source = build_json["source"][offset]
flattened_source = f"pragma solidity {version};{flattened_source}\n\n{source}\n"

f = open( 'output.sol', 'w' )
f.write(flattened_source)
f.close()

[Macarse]

@iamdefinitelyahuman you force pushed a rebase?

[matnad]

Commit included in #914. Closing this.