fix: increment TxCountByAddress once per tx

[jmhrpr]

closes #71

TxCountByAddress now increments the tx counter once per tx for every address in the transaction inputs and outputs by maintaining a set of already-seen addresses while processing each transaction. For each address, if it is not included in the seen-addresses set then increment the counter and insert the address into the set.

I wasn't sure if I should build the set then iterate over each address to do the send, or to maybe build the prefix before trying the insert into the set to avoid the clone, but I think the current implementation was the best option.

[jmhrpr]

It also tracks invalid transactions. I guess there's not really a definition on how you count invalid transactions. If we want to be extra-precise maybe for invalid transactions we check the collateral inputs and collateral outputs instead of the standard inputs and outputs.