hs-cpp: Revert "Remove hspocket from this branch (tabs-cpp)"

This reverts commit c9144c625f466338c5216d674a495f2349320458.
Fix fillPolygonSetFromEdges
hs: enable build
hs: trim spiral
hs: cleanup
Generalize AccumulateWindingNumber
Fix bugs. Add combinePolygonSet() and rawOffsetPolygonSet().
hspocket
Generalize SetNext to CombinePairs
Speed up vPocket