For each transaction allow to click on it and show lots of further
details about it.
This also fixes various bugs and adds some basic helper methods in
various places.
The QML is barely functional, getting the right data exposed was the
only goal today.
When a transaction is received by the p2pnet layer via a simple INV/
GetData we now process this and properly lock the outputs it spent to
avoid creating double spending transactions.
One task is left: properly recognize when a mined transaction
invalidates another transaction (like an unconfirmed one) and update the
datastructures.
The code to re-org all transactions in a block so transactions that
depend on others are processed after those they depend on had a silly
bug (missing line), fixed that but also made it unit-testable to
demonstrate the bug.