Translate ziggurat algorithms for normal and exponential variates to Julia.

This pull request removes the C file that computes normal variates in favor of a translation to Julia. On julia.mit.edu the implementation in Julia was 25 pct. faster which I can't really explain why. On my MacBook, they are approximately equally fast.

The tables necessary for calculating the normal variates are made in `BigFloat` and finally translated to `Uint64` and `Float64` thereby making them identical on 32 and 64 bit systems without storing the hardcoded tables as we done for about a week.

The server is busy with other computations, and therefore I haven't run BigCrush on the normal and exponential variates yet, but I have tried the test that the `rand` fails, see #6464. Surprisingly, the normal variates don't fail the test.