Getting txHash along with the contract logs

[r0wdy1]

As of now (0.18.0) there are some flaws with Contract.events method :

• there seems to be no way to get the hash of transaction associated wit a specific event ( although the original spec and the log struct model has a field and the data itself is actually retrieved from the node), which makes it impossible to get CallData for a specific emitted event instance
• blockFrom, blockTo, blockHash and address filled are hardcoded as blank, so from my experience such a query wouldn't be executed by Infura at all
• Corresponding builder functions for blockFrom, blockTo, blockHash fields receive values, not options, so there is additional complexity when creating filter

I tried my best ( please be patient, this is my first PR) to address aforementioned issues, may be not in a best way. I'm not really excited about making a new type for events with meta, the current idea with tuples, that matches event signature, seems really elegant, but unfortunately the txHash is actually necessary is lot's of cases