Allow custom separator for line numbers
Allow custom separator for line numbers

the number_lines highlighter accepts a -separator <arg> switch
to change the default '│' separator.

Fixes #295

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