anchor.diff:   * +show_matching+: highlight matching char of the character under the selections
          cursor using +MatchingChar+ face.
    * +number_lines+: show line numbers
  - * +fill <face>+: fill using given face, mostly useful with region highlighters
  + * +fill <face>+: fill using given face, mostly useful with the +regions+ highlighter
          (see below)
   
   Highlighting Groups
  
positive.code: construct in kakoune accept nested +{ ... }+ so +%sh{ ... { ... } ... }+ is valid.
  this region can be defined with:
  
  -------------------------------------
  addhl region shell_expand %sh\{ \} \{
  -------------------------------------
  
  It then provides a group named +content+ which can be filled with other highlighters
  that will only be applied on the given regions.
  
  -------------------------------------
  addhl -group shell_expand/content ...
  -------------------------------------
  
  The +multi_region+ highlighter is even more powerfull, it can segment the buffer
  in non overlapping regions.
  
  -------------------------------------------------------------------------
  addhl multi_region <name> <region_name1> <opening1> <closing1> <recurse1> \
                            <region_name2> <opening2> <closing2> <recurse2>...
  -------------------------------------------------------------------------
  
  defines multiple regions in which other highlighters can be added
  
  
negative.code: 
  That matches the rule governing most programming language parsing.
  
  +regions+ also supports a +-default <default_region>+ switch to define the
  default region, when no other region matches the current buffer range.
  
  most programming languages can then be properly highlighted using a +regions+
  highlighter as root:
  
  -----------------------------------------------------------------
  