P.Shell documentation and add missing unsafePrompt export
P.Shell documentation and add missing unsafePrompt export

Ignore-this: a03992ffdc9c1a0f5bfa6dafc453b587

Haddock (version 2.9.2 at least) does not attach documentation to any of a b or
c when given:

    -- | documentation
    a,b,c :: X

darcs-hash:20111207163951-1499c-63c977052b16fcd79857712ac39bd155cb6461d1

yzhou61/xmonad-contrib,yzhou61/xmonad-contrib,yzhou61/xmonad-contrib