anchor.diff:  Highlighters are often defined for a specific filetype, and it makes then sense to
   share the highlighters between all the windows on the same filetypes.
   
  -A shared highlighter can be defined with
  -
  ------------------------
  -defhl <shared_hl_name>
  ------------------------
  -
  -Highlighters can be added to it using the regular +:addhl+ command, with the
  -+-def-group <shared_hl_name>+ option.
  +A shared highlighter can be defined with the +:addhl+ command
  +
  +------------------------------
  +addhl -group /<group_name> ...
  +------------------------------
  +
  +when the group switch values starts with a '/', it references a group in the
  +shared highlighters, rather than the window highlighters.
  +
  +The common case would be to create a named shared group, and then fill it
  +with highlighters:
  +
  +---------------------------
  +addhl -group / group <name>
  +addhl -group /name regex ...
  +---------------------------
   
   It can then be referenced in a window using the +ref+ highlighter.
   
  ---------------------------
  -addhl ref <shared_hl_name>
  ---------------------------
  +----------------
  +addhl ref <name>
  +----------------
  +
  +the +ref+ can reference any named highlighter in the shared namespace.
   
   Hooks
   -----
  
positive.code: 
  the +:edit+ command can take a -fifo parameter:
  
  -----------------------------------
  :edit -fifo <filename> <buffername>
  -----------------------------------
  
  in this case, a buffer named +<buffername>+ is created which reads its content
  from fifo +<filename>+. When the fifo is written to, the buffer is automatically
  updated.
  
  This is very useful for running some commands asynchronously while displaying
  their result in a buffer. See rc/make.kak and rc/grep.kak for examples.
  
negative.code: :rmhl <highlighter_id>
  ----------------------
  
  general highlighters are:
  
   * +regex <ex> <color>...+: highlight a regex, takes the regex as first parameter,
         followed by any number of color parameters. color format is:
         <capture_id>:<fg_color>[,<bg_color>]
  