add etherscan function to ignore/remove unused contracts

[rmi7]

fixes #246

[rmi7]

changing this to != will make the mypy error go away. But then pylint will error saying it needs to be is not..

[0xalpharush]

Suggested change

	root_file_path = None
	base_path = ""
	for file_path, file_ast in compilation_unit.asts.items():
	if root_file_path is not None: # already found target contract
	break
	for node in file_ast["nodes"]:
	if node["nodeType"] == "ContractDefinition" and node["name"] == root_contract_name:
	root_file_path = file_path
	base_path = file_path.replace(file_ast["absolutePath"], "")
	break
	if root_file_path is None:
	# we could not find a contract with that name in any of the files
	return
	root_file_path = None
	found = False
	base_path = ""
	for file_path, file_ast in compilation_unit.asts.items():
	if found: # already found target contract
	break
	for node in file_ast["nodes"]:
	if node["nodeType"] == "ContractDefinition" and node["name"] == root_contract_name:
	root_file_path = file_path
	found = True
	base_path = file_path.replace(file_ast["absolutePath"], "")
	break
	if not found:
	# we could not find a contract with that name in any of the files
	return