Feature/method get transaction only returns in wallet transactions

[bridgedragon]

Description

The method getTransaction has been standardized to be run for any transaction (not only in-wallet ones).

• At first I tought I could make the method work with ElectrumX-ElectRs RPC. This could be useful in a future when issue Remove electrum completely #110 will be merged, and adds the possibility of disabling bitcoind -txindex, saving precious hard disk space (cool cool cool).
• It wasn't that cool... ElectRs does not index block height of a transaction... So, for that reason, we can't remove the -txindex, and it can't work without -txindex. (More on: Implement blockchain.transaction.get verbose support Blockstream/electrs#36). - my joy in a well :'(
• I left the methods and classes that can be used in resolving issue Remove electrum completely #110, allowing to call ElectRs Rpc directly.
• I realized that issue Abstract and standarize getTransaction() method #27 had a lot of disadvantages while I was coding this: If transaction are broken down in senders and destinations, it makes us work with decimal numbers and a lot of potential errors. Not cool. So, instead of "transactions", the getTransaction method now returns "inputs" and "outputs", with "address" and "amount" fields on each one. If i/o is not standard, null is returned.

Fixes #88

Dependencies (if any)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Good practices to consider

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[0xp3gasus]

No need to store the string value, just return the string value in response variable, "fee":str(transactionDetails["fee"])

[bridgedragon]

I disagree with this, because we are converting all elements in the array at once. I do not want to mix str variables with not-str ones in the same array.

[phoenix-web3]

The thing is that the behaviour is the same if you delete this line and add "fee":str(transactionDetails["fee"]) in line 434

[phoenix-web3]

After the requested changes of @swapper-pegasus this can be merged

Thanks @bridgedragon , beautiful code!