horizontal and vertical scrolloff

[Wiener234]

The idea/issue behind this feature is, that when using the terminal on only half of the screen with a line width of 80 the view will scroll to the right if you have a scrolloff=999 to center the line you edit. That would be desirable for the vertical but if i can fit 80 symbols on screen without scrolling and still scroll loosing the first symbols of my line it makes it harder to work with, because i don't see the beginning of the line.

So having a scrolloff for the vertical and one for the horizontal would solve the problem and give the user more ability to customize his editing experience.