Add option to have arrow on selected line as well as current line in source window

[jcul]

Sometimes it can be difficult to see which line you have selected in the source window.

Thought would be useful to have option to have a second arrow on the current highlighted line.

Also added option to allow the arrow color to be specified separately to the selected line color.

set arrowstyle=long
set arrowselectedline
# highlight SelectedLineArrow ctermfg=Blue

[mikesart]

I think Bob got most of this functionality in. Please give it a try and if not enter a new bug. Thanks jcul.