Continue monitoring blockchain transactions after restart

[ralph-pichler]

If a node terminates after sending a transaction or before enough confirmations have been reached we should continue monitoring this transaction after it restarts.

[Eknir]

@ralph-pichler , what is the status here? Could you link the PR in which you are working on solving this issue (partly)? Thanks!

[ralph-pichler]

A form of this has been implemented in #2089. However the PR is huge and will be split into smaller ones. There is also more testing and refactoring work to do.