* block sums and reworked block validation
read and write block_sums
refactor validate on both block and txhashset
write block_sum on fast sync
we store the kernel_sum (need to account for the offset)
* block_sums
* rustfmt
* cleanup
* allow selecting a commit while providing a key index
* added static reference to libsecp that can be called throughout
* don't serialise rangeproof to json if it's not desired
