Unrolled while loop in readVarLong.

(cherry picked from commit 45ffb1ae3c0527aae50502741a3585c411875b9a)
Signed-off-by: Ankur Dave <ankurdave@gmail.com>
Use murmur3 hash for open hashset.

(cherry picked from commit 212ff6834515543163aa63a3f4f762ebe641f8ca)
Signed-off-by: Ankur Dave <ankurdave@gmail.com>
Merge pull request #103 from amplab/optimizations

Optimizations cherry-picked from SIGMOD branches