PRNG + LCG chapters

[leios]

This is a draft PR for the next set of chapters. It will include the following:

• [ ] An intro to RNG
  • [ ] a discussion of where RNG is used in different fields
  • [ ] quick histogram check to see how random your RNG is
• [ ] Diehard tests
  • [ ] Birthday spacings
  • [ ] Overlapping permutations
  • [ ] Ranks of matrices
  • [ ] Monkey tests
  • [ ] Count the 1s
  • [ ] Parking lot test
  • [ ] Minimum distance test
  • [ ] Random spheres test
  • [ ] The squeeze test
  • [ ] Overlapping sums test
  • [ ] Runs test
  • [ ] The craps test
• [ ] Linear Congruential Generators
  • [ ] Explain why they might be used in CG applications / GPU kernels (due to other RNG methods being cumbersome)

Might be biting off a bit too much, but I've been wanting to do diehard tests forever now and it'll be fun creating the testsuite.

[Amaras]

Idea: add Linear-Feedback Shift Registers as a (cheap) hardware PRNG, although it can be quite weak as a PRNG