Function bitcoin_indexed_chain::guess_verification_progress

pub fn guess_verification_progress(
    data: &ChainTxData,
    pindex: Arc<BlockIndex>
) -> f64

| Guess verification progress (as a fraction | between 0.0=genesis and 1.0=current | tip). |

| Guess how far we are in the verification | process at the given block index require | cs_main if pindex has not been validated yet | (because nChainTx might be unset)