anchor.diff:  accessed through %reg{<register>} and %opt{<option>} syntax.
   
   for example you can display last search pattern with
  +-------------
   :echo %reg{/}
  +-------------
   
   Defining Commands
   -----------------
   
  -new commands can be defined using the *def* command.
  -
  +new commands can be defined using the +def+ command.
  +------------------------------
   :def <command_name> <commands>
  -
  +------------------------------
   <commands> is a string containing the commands to execute
   
   def can also takes some flags:
  - * *-env-params*: pass parameters given to commands in the environement as
  +
  + * +-env-params+: pass parameters given to commands in the environement as
                     kak_paramN with N the parameter number
  - * *-shell-params*: pass parameters given to commands as positional parameters
  + * +-shell-params+: pass parameters given to commands as positional parameters
                       to any shell expansions used in the command.
  - * *-file-completion*: try file completion on any parameter passed
  + * +-file-completion+: try file completion on any parameter passed
                          to this command
  - * *-shell-completion*: following string is a shell command which takes
  + * +-shell-completion+: following string is a shell command which takes
                           parameters as positional params and output one
                           completion candidate per line.
  - * *-allow-override*: allow the new command to replace an exisiting one
  + * +-allow-override+: allow the new command to replace an exisiting one
                         with the same name.
   
   Using shell expansion permits to define complex commands or to access
   kakoune state:
  -
  +------------------------------------------------------
   :def print_selection %{ echo %sh{ ${kak_selection} } }
  -
  +------------------------------------------------------
   Some helper commands can be used to define composite commands:
   
  - * menu <label1> <commands1> <label2> <commands2>...: display a menu using
  + * +menu <label1> <commands1> <label2> <commands2>...+: display a menu using
        labels, the selected label's commands are executed.
  - * try <commands> catch <on_error_commands>: prevent an error in <commands>
  + * +try <commands> catch <on_error_commands>+: prevent an error in <commands>
        from aborting the whole commands execution, execute <on_error_commands>
        instead.
   
  
positive.code: FIFO Buffer
  -----------
  
  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 <filename>. When filename is appended 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: 
  Kakoune support three string syntax:
  
   * +"strings" and \'strings\'+: classic strings, use \' or \" to escape the
        separator.
  
   * +%\{strings\}+: these strings are very usefull when entering commands
  
     - the '{' and '}' delimiter are configurable: you can use any non
       alphanumeric character. like %[string], %<string>, %(string), %~string~
       or %!string!...
     - if the character following the % is one of {[(<, then
       the closing one is the matching }])>, and these delimiters in the string
       need not to be escaped if the contained delimiters are balanced.
       for example +%{ roger {}; }+ is a valid string.
  
  Highlighters
  ------------
  
  Manipulation of the displayed text is done through highlighters, which can be added
  or removed with the command
  -----------------------------------------------------
  :addhl <highlighter_name> <highlighter_parameters...>
  -----------------------------------------------------
  and
  ----------------------
  :rmhl <highlighter_id>
  ----------------------
  
  existing highlighters are:
  
   * +highlight_selections+: used to make current selection visible
   * +expand_tabs+: expand tabs to next 8 multiple column (to make configurable)
   * +number_lines+: show line numbers
   * +group+: highlighter group, containing other highlighters. takes one
              parameter, <group_name>. useful when multiple highlighters work
              together and need to be removed as one. Adding and removing from
              a group can be done using
              `:addhl -group <group> <highlighter_name> <highlighter_parameters...>`
              `:rmhl  -group <group> <highlighter_name>`
   * +regex+: highlight a regex, takes the regex as first parameter, followed by
              any number of color spec parameters.
              color spec format is: <capture_id>:<fg_color>[,<bg_color>]
              For example: `:addhl regex //(\h+TODO:)?[^\n]+ 0:cyan 1:yellow,red`
              will highlight C++ style comments in cyan, with an eventual
              'TODO:' in yellow on red background.
  
  