[slim-vim] Arguments for replace-lines and buffer-lines

[Eirik A. Nygaard]

buffer-lines takes three optional arguments, buffer, start and end, in that
order. While replace-lines takes three keyword arguments, :start, :end and
:buffer. Would anyone object to using keyword as well, being able to just
specify the start. As of now you always have to specify the buffer, which seems
a bit redundant at times.

-- 
Eirik Nygaard