Auto-bump script idea

[FrancisPouliot]

An idea for a new script to automatically bump the fee of a transaction based on expected confirmation times vs blocks passed since transaction.

1. Auto-bump would be a config in cyphernonde using the proxycron
2. When doing a transaction, we record the fee and expected number of blocks (n)
3. We keep watch of the transaction in the mempool
4. We set a threshold after with we will autobump (x %)
5. Once the transaction has reached (n + x%) we call the estimate smartfee feature to get the new estimate fees required for the same amount of estimated blocks, than we substract the existing fees, and call bumpfee feature and add what is missing.

This would allow us to set lower fees, and offset having a transaction stuck in the mempool because the fee has increased.

This is a very preliminary draft.

[Kexkey]

In the mean time, the bumpfee endpoint has been added to Cyphernode.