Refactor packing
Refactor packing

Use a map of Range -> BucketCollections, instead of just concatenating all BucketCollections together

IGV-2071

itenente/igv,godotgildor/igv,godotgildor/igv,godotgildor/igv,igvteam/igv,igvteam/igv,godotgildor/igv,amwenger/igv,igvteam/igv,amwenger/igv,itenente/igv,amwenger/igv,itenente/igv,itenente/igv,igvteam/igv,godotgildor/igv,itenente/igv,igvteam/igv,amwenger/igv,amwenger/igv