[Vim] Set column color at column 80.

Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>
[Vim] Map F10 to show name of highlight group.

Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>
[Vim] Remove trailing spaces.

Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>