remove unused variables, som error handling
Revert "remove unused variables, som error handling"

This reverts commit 7b456de07b2cc3bc5a61af17a22ea87a9dfbeaaf.
Revert "fix dependencies"

This reverts commit 35061adf15c03e3707858f531a39ea4fadb12c2e.
Revert "use snappy"

This reverts commit 847285515e03471f53aadb252321bc3d08966450.
Revert "use skipfile"

This reverts commit ed6d2663f94f10123676dbc3553af308f1fcb2cc.
use snappy
new chained batch that compresses earlier
refactor: DRY
remove unused variables
refactor, breaking: new schema-format & encoding-abstraction
compress in encoding.encode