1.0.43.63: storing function documentation under names as well

1.0.43.63: storing function documentation under names as well

 Since 1.0.29.24 we have stored function documentation exclusively in
 the function objects. Turns out this isn't a pure win:

   (setf (symbol-function 'foo) #'car)

   (setf (documentation 'foo 'function) "Return the name of frobniz.")

 should not change the docstring of #'CAR.

 So, when setting the docstring of a function name, store it in
 RANDOM-DOCUMENTATION instead of in the simple-fun.

 Conversely, when looking up the docstring for a function name, first
 look in RANDOM-DOCUMENTATION and only then in the bound function.