bug#8504: add more query-replace choice keys

[jidanni]

There should be a key to say "yes, replace this occurrence, but
keep the case exact"!

That way one wouldn't have to fiddle with any other variables and also
have the flexibility of two types of case policy, all within the same
query-replace session!

Query replacing x with Easting.

Type Space or `y' to replace one match, Delete or `n' to skip to next,
RET or `q' to exit, Period to replace one match and exit,
Comma to replace but not move point immediately,
C-r to enter recursive edit (C-M-c to get out again),
C-w to delete match and recursive edit,
C-l to clear the screen, redisplay, and offer same replacement again,
! to replace all remaining matches with no more questions,
^ to move point back to previous match,
E to edit the replacement string

Also E gave me Easting to edit, when it really should have gave me
EASTING, which it intended to use, depending on the string I was on.

Also E above doesn't say if editing it will change it for the rest of
the queries.

Maybe there should be a F to do that too.