bug#31615: 27.0; doc of `uncomment-region(-default)'

[Drew Adams <drew.adams@oracle.com>]

1. These two functions should not have the same doc string.  Function
`*-default' should say what is - the default value of
`uncomment-region-function'.

2. The doc strings should be much more specific about the behavior, in
particular wrt ARG.  Apparently the functions do nothing at all if ARG
is larger than the first sequence of comment chars in the region.

E.g. for a comment such as this one:

  ;; foo bar

(uncomment-region (line-beginning-position) (line-end-position) 3)

does nothing.  That's not obvious from the doc.  From the doc I'd get
the impression that I could be sure to remove all contiguous comment
chars from the beginning using `most-positive-fixnum' for ARG.

3. The doc string talks about "comment markers".  What's that?

4. Enhancement request: Provide a way to remove ALL comment chars and
all whitespace between them, up to the first non-comment char.  So each
of these lines, for example:

  ;; ;;; ; foo bar

  ; ; ; ; foo bar

  ;; ;; foo bar

  ;; foo bar

would be uncommented to this line:

  foo bar

That could be done, for example, by providing `all' as the value of ARG.


In GNU Emacs 27.0.50 (build 3, x86_64-w64-mingw32)
 of 2018-03-21
Repository revision: e70d0c9e66d7a8609450b2889869d16aeb0363b5
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
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 --without-compress-install -C 'CFLAGS=-O2 -static -g3''