By removing Address.Error, we remove a code smell.
This part of the code base was also not under any form of test.
Test data and tests have therefore been added verifying its behaviour in
both Wallet and Address tests.
The introduction of these two functions allow for the all the network
related code to be eventually removed from Transaction and Script.
Previously the result for non-standard transactions was undefined
behaviour. This change mandates that an exception is thrown if a
non-standard transaction is input.
Daniel Cousens