[testnet2] Store output sum (#1043)

* 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

chain/tests/data_file_integrity.rs

@@ -86,7 +86,6 @@ fn data_files() {
 				global::sizeshift(),
 			).unwrap();
 
-			// let prev_bhash = b.header.previous;
 			let bhash = b.hash();
 			chain
 				.process_block(b.clone(), chain::Options::MINE)