RANDOM &co documentation

[Nikodemus Siivola]

1. The fact that initial value of *RANDOM-STATE* is consistent is not documented.

2. SEED-RANDOM-STATE is not mentioned in the manual, nor is random number generation discussed there otherwise.

[Lutz Euler (lutz-euler)]

SEED-RANDOM-STATE has already been added to the manual,
shortly after this bug was opened. Its formatting is broken there;
I have just committed a fix for that.

[Lutz Euler (lutz-euler)]

I add a patch for review that adds a manual section
dealing with random number generation.

[Lutz Euler (lutz-euler)]

In light of the recent discussion about the properties
of random floats on sbcl-help I have added some notes
about these to the patch. Attached is the new version.

[Lutz Euler (lutz-euler)]

I reworded the first paragraph about random floats,
trying to get ideas detailed in the meantime by Paul
in the above-mentioned sbcl-help discussion across.

[Nikodemus Siivola (nikodemus)]

+1

[Lutz Euler (lutz-euler)]

I have just committed the patch from #4,
with a small grammatical correction.