solidity methods jumps: fix

[sevenzing]

There is a tool for parsing some of compiler outputs to provide mapping from solidity public method to the source code place. Some changes are required in this tool:

• look for whatsabi implementation of finding selectors in bytecode, add missing logic to the find_selector function
• Write tests that cover different situations with selectors, 0x00112233, 0x00001122 etc
• remove evm.methods_indetifiers from input of function, get methods from abi (filter only functions and hash its signatures)
• [OPTIONAL] For now we use output.sources from compilation to get file ids, however we don't have those data in database :( So, if possible, find a way to get mapping file_id -> file_path without compiling contract. Maybe you can just sort all sources ?) I suggest to look at solidity source code.

Not sure where to store this code, you can make PR in my local repo OR you can store code locally and then use it for the smart-contract-verifier task: [todo: add issue link]