AtomicMarkableReference: move implementation to Edge module

Author: ianks

lib/concurrent-edge.rb

@@ -8,3 +8,4 @@
 
 require 'concurrent/edge/future'
 require 'concurrent/edge/lock_free_stack'
+require 'concurrent/edge/atomic_markable_reference'

lib/concurrent.rb

@@ -9,7 +9,6 @@
 require 'concurrent/executors'
 require 'concurrent/utilities'
 
-require 'concurrent/atomic/atomic_markable_reference'
 require 'concurrent/atomic/atomic_reference'
 require 'concurrent/atom'
 require 'concurrent/async'
@@ -28,7 +27,7 @@
 require 'concurrent/tvar'
 
 # @!macro [new] monotonic_clock_warning
-# 
+#
 #   @note Time calculations one all platforms and languages are sensitive to
 #     changes to the system clock. To alleviate the potential problems
 #     associated with changing the system clock while an application is running,
@@ -47,9 +46,9 @@
 
 # Modern concurrency tools for Ruby. Inspired by Erlang, Clojure, Scala, Haskell,
 # F#, C#, Java, and classic concurrency patterns.
-# 
+#
 # The design goals of this gem are:
-# 
+#
 # * Stay true to the spirit of the languages providing inspiration
 # * But implement in a way that makes sense for Ruby
 # * Keep the semantics as idiomatic Ruby as possible