* Make sure EmbedMultipleConfs is deterministic for very large seeds and a seed of 0.
Fixing two distinct bugs:
- A randomSeed of 0 didn't use '0' as the seed even though the
documentation said that it should.
- Very large seeds could overflow the 'int' representation during
calculation of a new internal seed. This would make
EmbedMultipleConfs non-deterministic even though the user provided a
valid seed.
* Adding a C++ test for case pull request #1635.