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: 
  That matches the rule governing most programming language parsing.
  
  +multi_region+ 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 +multi_region+
  highlighter as root:
  
  -----------------------------------------------------------------
  
negative.code: addhl -group <name>/<subname> <type> <params>...
  ------------------------------------------------
  
  Regions highlighters
  ~~~~~~~~~~~~~~~~~~~~
  
  A special highlighter provide a way to segment the buffer into regions, which are
  to be highlighted differently.
  
  A region is defined by 4 parametes:
  
  ------------------------------------
  <name> <opening> <closing> <recurse>
  ------------------------------------
  
  +name+ is user defined, +opening+, +closing+ and +recurse+ are regexes.
  
   * +opening+ defines the region start text
   * +closing+ defines the region end text
  