[Feature] Random Number Generation

[bjoernd]

Is your feature request related to a problem? Please describe.
I want to create random numbers.

Describe the solution you'd like
Add a PRNG and random/srand functions to KTF.

Additional context
We may want configurable selection of PRNG or a real RNG depending on use case.

[nmanthey]

Does the PRNG need to be fast, statistically robust, thread safe?

[bjoernd]

It should just magically work! We might even have multiple variants (selected at compile time?). My use case is: I want to seed the RNG and be able to reproduce the sequence of random numbers (that's why I need a PRNG rather than real randomness). I will likely not use it concurrently.

…

[wipawel]

For x86 we can employ RDSEED and RDRAND instructions for the PRNG.

[nmanthey]

I implemented a simple one, which should work for basic, test-like, work loads.

[bjoernd]

RNG implemented via #101

We might still want to use hardware random number generation later.