Specifically check for 192-bit option in std.random.XorshiftEngine.
Correct typo in Xorshift32 which was leading to non-uniform behaviour.

The original typo derives directly from George Marsaglia's paper
introducing the Xorshift RNGs.  The original checking values, derived
from that code, thus also reflect the typo.

A corrected version of the reference code is available from
https://github.com/WebDrake/xorshift/ and has been used to
generate the updated checking values.
Correct typo in Xorshift160 which was leading to non-uniform behaviour.

The original typo derives directly from George Marsaglia's paper
introducing the Xorshift RNGs.  The original checking values, derived
from that code, thus also reflect the typo.

A corrected version of the reference code is available from
https://github.com/WebDrake/xorshift/ and has been used to
generate the updated checking values.
Merge pull request #1403 from WebDrake/xorshift

Fix Issue 10550 - Xorshift32 and Xorshift160 do not generate uniformly-distributed random numbers
Double safety check for Xorshift bit values.
Make Xorshift bit-related error messages more informative.
Add workaround to fix issue 10567

Currently VariantN does not support const objects comparison. So just add specialized opCmp member and use cast().
Merge pull request #1404 from WebDrake/xorshift

Double safety check for Xorshift bit values.
Merge pull request #1405 from 9rnsr/fix10567

Add workaround to fix issue 10567