bug#13175: 24.3.50; Isearch: doc of `C-M-w' and interaction with Backspace (`DEL')

[Drew Adams]

In Isearch:

`C-M-w' deletes the last char from the search string.  Following this
with `DEL' adds that char back!  Is this behavior intended (a feature)
or a bug?

Seems like a useful feature, to me.  But AFAICT, it is documented
nowhere.

The doc should, in addition to mentioning this, document `DEL' and
`C-M-w' together.  Do not document `C-M-w' only in the context of
yanking - that makes no sense.

And that doc of both together should point out clearly what the
differences are, including the fact that `DEL' can cancel searching but
`C-M-w' never does that.

In GNU Emacs 24.3.50.1 (i386-mingw-nt5.1.2600)
 of 2012-12-13 on ODIEONE
Bzr revision: 111211 eggert@cs.ucla.edu-20121213021749-eyqqen0ewhn2hogq
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -IC:/Devel/emacs/build/include -Wall -Wextra -Wno-sign-compare
 -Wno-type-limits -Wno-missing-field-initializers -Wno-pointer-sign
 -Wdeclaration-after-statement --ldflags -LC:/Devel/emacs/build/lib'