ECHeader
aarifullin/frostfs-sdk-go:feat/ecHeader_parentSplit
master
* Introduce `parentSplitID`, `parentSplitParentID` fields for `ECHeader`; * Fix ECHeader's constructor; * Fix `Split` and `Reconstruct`; * Add unit-tests. Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>