jeffreys prior (prior.py)

[jllanfranchi]

• Merely refers to "Sivia p. 125"; fix this reference to be more usable
• Add documentation in the code enough that the user knows the function implemented, and supplemental info can require a book, but discovering what one-letter parameters like "A" and "B" are shouldn't require checking a book out from the library, or reading the code. Furthermore, and maybe more importantly, a Jeffreys prior is a somewhat general concept, so at least say what particular situation this Jeffreys prior is designed to address.
• The prior is named after Jeffreys (his name has a trailing "s") but it is not used as belonging to him, so there's no possessive apostrophe needed (think "Cantor set" as opposed to "Newton's method")

[LeanderFischer]

What exactly is jeffreys prior anyway? I guess this really could use some better docu..