TX confirmation priority update

Please be informed that, due to the EXCEPTIONAL increase of TX fees (specially on BTC blockchain), we lowered the "confirmation priority" of our algorithm to avoid huge impact of the fees over total TX value. This also means the expected confirmation time might temporary increase, until the blockchain congestion will normalize.

We would also take the opportunity to anticipate a new tool, that will be formally announced on coming days, that will allow our customer to set the preferred "priority" for the confirmation of the transactions:

- low priority (lower network fees, longer to confirm)
- normal (default setting, good balance between confirmation time and network fees)
- high priority (higher network fees, faster to confirm)