Problem: hard to view an existing buffer in the preview window
Solution: add the :pbuffer command (Yinzuo Jiang)
Similar as `:pedit` and `:buffer` command. `:pbuffer` edits buffer [N]
from the buffer list in the preview window.
`:pbuffer` can also open special buffer, for example terminal buffer.
closes: #16222
Signed-off-by: Yinzuo Jiang <jiangyinzuo@foxmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
a2a2fe841e
