Fetch github sources

[DeFiYaco]

When library is imported in Remix, metadata contains github URL of that file. We can fetch it and compare its keccak to the one inside metadata file.

Example:

"https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/EnumerableMap.sol": {
            "keccak256": "0xd56ced96976a99130de28a6adfb6d56e8073403a0d134fbab6428b568f12f337",
            "license": "MIT",
            "urls": [
                "bzz-raw://e6d5abf1220727cc3fed50b23e2a2ee09d6f877db380cab45d967b3d989822df",
"dweb:/ipfs/QmZU816XJg1jTZnvxsJE9bgwud2LRAjyvuWhnMCEjCKWiV"
]
}    

_{View in Huly HI-142}