Improve transaction review when interacting with contracts

[arobsn]

From TG:

When signing a tx which has a p2s input and p2s output (same address) any assets in this address are shown as being sent to this address in the tx overview (not leaving wallet but shows as being sent). This can confuse users as it might be large amounts that they dont expect

We probably need a major refactoring of the TransactionInterpreter class to do a full analysis and try to determine how inputs are related to outputs and display it more assertively to the user.