Today fish_cursor_selection_mode controls whether selection mode includes
the cursor. Since it's by default only used for Vi mode, perhaps use it to
also decide whether it should be allowed to select one-past the last character.
Not allowing to select to select one-past the last character is much nicer
in Vi mode. Unfortunately Vi mode sometimes needs to temporarily select
past end (using forward-single-char and such), so reset fish_cursor_selection_mode
for the duration of the binding.
Also fix other things like cursor placement after yank/yank-pop.
Closes#10286Closes#3299
Multiline search strings are weirdly broken (inserting control characters
in the command line) and probably not very useful anyway.
On the other hand I often want to compose a multi-line command
from single-line commands I ran previously.
Let's support this case by limiting the initial search string to the current
line; and replace only that line.
Alternatively this could operate on jobs (that is, replace a surrounding
"foo | bar") instead of using line boundaries.
