Allow seeding of Simplex noise

[kitsu]

You currently have the permutation table defined as:

private static readonly short[] P = 
{
    151,160,137,91,90,15, ...
};

If you instead randomly select those values you should get random simplex noise.

Alternately you can shuffle the table while expanding the permutations, see this implementation for a seeded simplex: https://github.com/everbytes/LibNoise/blob/master/src/LibNoise.NET35/Primitive/ImprovedPerlin.cs

[MarkuBu]

Wat to report this issue too. Simplex noise should have a seed.

[rthome]

I definitely agree that the Simplex module sould provide the same set of properties that the other noise source module provide (Seed, Frequency, Lacunarity, etc).

The thing is, back when i was translating the C++ of the original libNoise to C#, I had this implementation of Simplex lying around - so I just added it as a module. But it's not part of the original C++ and I (unfortunately, perhaps) didn't take the time to properly integrate it into NoiseGenerator or set up the usual properties.

I'll look into it, but I don't know whether I have the time to properly refactor the module. If it's a pressing matter, I'd be happy to accept contributions ;-)