implements ReadFrom and WriteTo for Snapshot

dapps/valuetransfers/packages/balance/balance.go

dapps/valuetransfers/packages/balance/balance_test.go

dapps/valuetransfers/packages/tangle/ledgerstate.go

dapps/valuetransfers/packages/tangle/snapshot.go

dapps/valuetransfers/packages/tangle/tangle.go

dapps/valuetransfers/packages/tangle/tangle_snapshot_test.go

dapps/valuetransfers/packages/tangle/tangle_test.go

plugins/dashboard/payload_handler.go

plugins/webapi/value/unspentoutputs/handler.go

plugins/webapi/value/utils/transaction_handler.go