Lower precision for some columns

[murchandamus]

• There are a number of columns in the result that output amounts, these should have a precision of 8 decimals (e.g. Cost to Empty and Total Cost have 12, but that is unnecessary).
• Averaged counts of UTXOs and inputs could be reduced to 2 decimals instead of 10 (Mean #UTXO and Mean Input Size).
• Mean Change Value has a precision of 12 decimals, but could probably just be shown with sat precision
• The standard deviations could be reduced to four decimal precision instead of 11 (Std. Dev. of Input Size, Std. Dev. of Change Value)
• Mean Fees per Withdraw has currently 16 decimals precision, it could probably be presented in satoshis with a two decimal precision