Speed up for D.d by ~10%

Modifications:
- removed some void initializers that had no impact on performance.
- random number generator now skips xor with 1 on overflow.
- D specific rearrangement of checkColl(), for better LLVM omptimization (-10% off total runtime).
- lines of code excluding empty and comment: 100
Merge pull request #18 from mleise/patch-1

Speed up for D.d by ~10%