Clean up and improve the commenting functions
Clean up and improve the commenting functions

Simplifies the selection commenting function, add proper draft options
to the exec statements, and make the uncommenting bit keep the selection.

Add a function that comments the current line with "//", uncommenting is
supported as well.

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