Drop unused markup parameter from Formatter hierarchy

No caller ever passes a non-nil `markup` to any formatter constructor —
every formatter creates its own `RDoc::Markup.new` internally.

Remove the `markup` parameter from `Formatter#initialize` and all
subclasses: `ToHtml`, `ToHtmlCrossref`, `ToHtmlSnippet`, `ToRdoc`,
`ToLabel`, `ToTtOnly`, `ToAnsi`, `ToBs`, `ToMarkdown`.

Also remove the dead `markup` variable in `Heading.to_html` that was
configured with crossref regexp handling but never passed to the
formatter.

Author: st0012

lib/rdoc/markup/formatter.rb

@@ -48,10 +48,10 @@ def self.gen_relative_url(path, target)
   ##
   # Creates a new Formatter
 
-  def initialize(options, markup = nil)
+  def initialize(options)
     @options = options
 
-    @markup = markup || RDoc::Markup.new
+    @markup = RDoc::Markup.new
 
     @from_path = '.'
   end

lib/rdoc/markup/heading.rb

@@ -52,9 +52,6 @@ def self.to_label
       #: () -> RDoc::Markup::ToHtml
       def self.to_html
         @to_html ||= begin
-          markup = Markup.new
-          markup.add_regexp_handling CrossReference::CROSSREF_REGEXP, :CROSSREF
-
           to_html = Markup::ToHtml.new nil
 
           def to_html.handle_regexp_CROSSREF(text)

lib/rdoc/markup/to_ansi.rb

@@ -7,7 +7,7 @@ class RDoc::Markup::ToAnsi < RDoc::Markup::ToRdoc
   ##
   # Creates a new ToAnsi visitor that is ready to output vibrant ANSI color!
 
-  def initialize(markup = nil)
+  def initialize
     super
 
     @headings.clear

lib/rdoc/markup/to_bs.rb

@@ -10,7 +10,7 @@ class RDoc::Markup::ToBs < RDoc::Markup::ToRdoc
   ##
   # Returns a new ToBs that is ready for hot backspace action!
 
-  def initialize(markup = nil)
+  def initialize
     super
 
     @in_b  = false

lib/rdoc/markup/to_html.rb

@@ -43,7 +43,7 @@ class RDoc::Markup::ToHtml < RDoc::Markup::Formatter
   ##
   # Creates a new formatter that will output HTML
 
-  def initialize(options, markup = nil)
+  def initialize(options)
     super
 
     @code_object = nil

lib/rdoc/markup/to_html_crossref.rb

@@ -29,10 +29,10 @@ class RDoc::Markup::ToHtmlCrossref < RDoc::Markup::ToHtml
   # references are removed unless +show_hash+ is true.  Only method names
   # preceded by '#' or '::' are linked, unless +hyperlink_all+ is true.
 
-  def initialize(options, from_path, context, markup = nil)
+  def initialize(options, from_path, context)
     raise ArgumentError, 'from_path cannot be nil' if from_path.nil?
 
-    super options, markup
+    super options
 
     @context       = context
     @from_path     = from_path

lib/rdoc/markup/to_html_snippet.rb

@@ -34,8 +34,8 @@ class RDoc::Markup::ToHtmlSnippet < RDoc::Markup::ToHtml
   # next word boundary after the given number of +characters+ or +paragraphs+
   # of text have been encountered.
 
-  def initialize(options, characters = 100, paragraphs = 3, markup = nil)
-    super options, markup
+  def initialize(options, characters = 100, paragraphs = 3)
+    super options
 
     @character_limit = characters
     @paragraph_limit = paragraphs

lib/rdoc/markup/to_label.rb

@@ -14,8 +14,8 @@ class RDoc::Markup::ToLabel < RDoc::Markup::Formatter
   ##
   # Creates a new formatter that will output HTML-safe labels
 
-  def initialize(markup = nil)
-    super nil, markup
+  def initialize
+    super nil
 
     @markup.add_regexp_handling RDoc::CrossReference::CROSSREF_REGEXP, :CROSSREF
 

lib/rdoc/markup/to_markdown.rb

@@ -9,7 +9,7 @@ class RDoc::Markup::ToMarkdown < RDoc::Markup::ToRdoc
   ##
   # Creates a new formatter that will output Markdown format text
 
-  def initialize(markup = nil)
+  def initialize
     super
 
     @headings[1] = ['# ',      '']

lib/rdoc/markup/to_rdoc.rb

@@ -52,8 +52,8 @@ class RDoc::Markup::ToRdoc < RDoc::Markup::Formatter
   ##
   # Creates a new formatter that will output (mostly) \RDoc markup
 
-  def initialize(markup = nil)
-    super nil, markup
+  def initialize
+    super nil
 
     @markup.add_regexp_handling(/\\\S/, :SUPPRESSED_CROSSREF)
     @width = 78