Change scrolloff behaviour, allow displaying pas the end of buffer
Change scrolloff behaviour, allow displaying pas the end of buffer

Fixes #306

occivink/kakoune,alpha123/kakoune,alpha123/kakoune,zakgreant/kakoune,mawww/kakoune,casimir/kakoune,lenormf/kakoune,alexherbo2/kakoune,jkonecny12/kakoune,occivink/kakoune,mawww/kakoune,Somasis/kakoune,zakgreant/kakoune,occivink/kakoune,mawww/kakoune,zakgreant/kakoune,jjthrash/kakoune,Asenar/kakoune,alpha123/kakoune,Somasis/kakoune,jjthrash/kakoune,jkonecny12/kakoune,jjthrash/kakoune,mawww/kakoune,danr/kakoune,alexherbo2/kakoune,flavius/kakoune,elegios/kakoune,elegios/kakoune,elegios/kakoune,danr/kakoune,alexherbo2/kakoune,jjthrash/kakoune,lenormf/kakoune,ekie/kakoune,casimir/kakoune,lenormf/kakoune,occivink/kakoune,elegios/kakoune,zakgreant/kakoune,casimir/kakoune,danr/kakoune,casimir/kakoune,lenormf/kakoune,flavius/kakoune,flavius/kakoune,alpha123/kakoune,Somasis/kakoune,Somasis/kakoune,flavius/kakoune,ekie/kakoune,jkonecny12/kakoune,ekie/kakoune,danr/kakoune,ekie/kakoune,Asenar/kakoune,Asenar/kakoune,jkonecny12/kakoune,Asenar/kakoune,alexherbo2/kakoune