Hi,

attached patch adds `current-line' and its tests. This new 
function returns the line number at given position ignoring 
narrowing.

I guess that `what-line' could be refactored using 
`current-line'. I can do that if you want.

Best, 

-- 
Damien Cassou
http://damiencassou.seasidehosting.st

"Success is the ability to go from one failure to another without
losing enthusiasm." --Winston Churchill