Improve visual_range segment
Do not use “rows” and “cols” in text

Reason: string “1 rows” is incorrect and I do not want to implement proper 
number handling (*proper* handling is *not* limited to plural/singular form like
in English).
Add tests for visual_range
Add fix for old Vims where getpos does not return list of integers
Merge pull request #957 from ZyX-I/better-visual-range

Improve visual_range segment