Aleth never clears transaction queue's "dropped transactions" list

[halfalicious]

Transactions which are dropped during transaction queue import are stored in TransactionQueue::m_dropped. A max size isn't enforced on m_dropped and m_dropped is only cleared when the entire Transaction Queue is cleared (TransactionQueue::clear), which doesn't happen during normal execution.

[chfast]

Why do we keep them?

[gumb0]

@chfast I think to immediately drop them withoud validation, if they come once again over the network

[chfast]

Some kind of ring buffer would be nicer here, don't you think?