bug#41692: 26.3; Enhancement request, `query-replace': let user use text at point as default

[Drew Adams]

Sorry, the defvar I suggested is not good, at
least for picking up the car of `search-ring' or
`regexp-search-ring'.  Wasn't thinking straight.

Maybe either another function-valued variable
(to be called) or a sexp-valued variable (to be
evalled).

The main suggestion is more user control over
(1) the list of default sources and (2) some
of the choices (e.g. one or two function-valued
vars).