refactored to use skewheap instead of pqueue

Signed-off-by: pjs <pjs@alum.mit.edu>

lib/simplekit.rb

 require 'rubygems'
-require 'pqueue'
+require 'skewheap'
 
 # Including SimpleKit gives you methods :run, :model_time, :schedule,
 # and :halt as mixins.  You <b>MUST NOT</b> provide your own implementations
@@ -25,7 +25,7 @@ module SimpleKit
   end
   
   # This class provides the computation engine for a discrete event
-  # simulation model. It uses RubyGem's PQueue class as the priority
+  # simulation model. It uses RubyGem's SkewHeap class as the priority
   # queue implementation for the pending events list.
   #
   # Users must create a model class which
@@ -36,7 +36,7 @@ module SimpleKit
 
     def initialize(the_model)
       @user_model = the_model
-      @event_list = PQueue.new
+      @event_list = SkewHeap.new
     end
 
     public
@@ -89,7 +89,7 @@ module SimpleKit
     end
 
     def <=> (other)
-      other.time <=> time
+      time <=> other.time
     end
   end