Fixed a bug in the GPU gather function of the BFS stepwise implementation.
Lowered the threashold that specifies the maximum size of the frontier.
Modified the bottom-up GPU kernel of the BFS stepwise algorithm to support partitioned edge memory type
Merge branch 'hybrid-bfs-stepwise' of github.com:ahgharaibeh/Totem into hybrid-bfs-stepwise
More optimizations to the bottom-up kernel of the BFS stepwise algorithm.
Optimized some of the bitmap operations to get rid of extra calculations when accessing a bit in the bitmap
Merge branch 'hybrid-bfs-stepwise' of github.com:ahgharaibeh/Totem into hybrid-bfs-stepwise
For BFS Stepwise, removed an uneccessary gather.