Fixes

	:new edit "file with spaces"

Closes mawww#1432

"new" runs "kak -c" which opens a recently used buffer.  More often
than not, I rather want to preserve the calling client's buffer and
selections. For example I might select a word and run "new" followed by
"grep" on the selected word. If the selection is preserved I can use
"new grep".  A similar scenario is "new lsp-definition".

Make "new" use the calling client's buffer and selections to support
such scenarios. Center the viewport with vv, matching "edit <file>
<line>".

Vim does this in <c-w><c-v>.

Another scenario is when I want to look at two regions from a file,
side-by-side.

My initial patch used the code below but Zz seems better:

	echo "try %|
	    buffer -- '$(printf %s "$kak_buffile" | sed "s/'/''/g; s/|/||/g")'
	    select $kak_selections_desc
	    execute-keys vv
	|"