bug#8682: 24.0.50; doc strings of `isearch-mode', `isearch-forward', etc.

[Drew Adams]

1. At a minimum, the doc string of `isearch-mode' should say something
like this:
 
FORWARD non-nil means forward search; nil means backward search.
REGEXP t means regexp search; nil means literal search.
OP-FUN means ???????
RECURSIVE-EDIT non-nil means recursive edit for a modal search.
WORD-P non-nil means word search; nil means ignore word boundaries.
 
And you can remove this sentence from the doc string - a function's doc
should, in general, not mention callers:
 
"It is called by the function `isearch-forward' and other related
functions."
 
(Also, some `isearch-mode' arguments should be renamed with `-P', to
indicate that they are boolean flags: FORWARD-P, REGEXP-P,
RECURSIVE-EDIT-P.)
 
OP-FUN: It corresponds to `isearch-op-fun', but there is no doc string
for `isearch-op-fun', and the accompanying source comment does not help
- it says only when `isearch-op-fun' is called, not what it is for or
how it is used.
 

2. Doc strings of `isearch-forward' etc. also need to describe their
args.  E.g. 
 
Non-interactively:
REGEXP-P means...
NO-RECURSIVE-EDIT means...
 
Again, NO-RECURSIVE-EDIT should be NO-RECURSIVE-EDIT-P, to indicate that
it is its truth value that is used (nil/non-nil).
 

3. More generally, isearch.el needs more and better doc strings.
 

In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2011-05-16 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.5) --no-opt --cflags
-Ic:/build/include'