Support lexing or carriage returns

Fixes #89.

ext/ragel/base_lexer.rl

@@ -46,7 +46,7 @@
     # stack.
     #
 
-    newline = '\n' | '\r\n';
+    newline = '\r\n' | '\n' | '\r';
 
     action count_newlines {
         if ( fc == '\n' ) lines++;

spec/oga/xml/lexer/elements_spec.rb

@@ -41,6 +41,14 @@ describe Oga::XML::Lexer do
         [:T_ELEM_END, nil, 2]
       ]
     end
+
+    it 'lexes an element with a carriage return in the open tag' do
+      lex("<p\r></p>").should == [
+        [:T_ELEM_START, nil, 1],
+        [:T_ELEM_NAME, 'p', 1],
+        [:T_ELEM_END, nil, 2]
+      ]
+    end
   end
 
   describe 'elements with attributes' do

spec/oga/xml/lexer/general_spec.rb

@@ -10,10 +10,18 @@ describe Oga::XML::Lexer do
       lex(' ').should == [[:T_TEXT, ' ', 1]]
     end
 
-    it 'lexes a newline' do
+    it 'lexes a Unix newline' do
       lex("\n").should == [[:T_TEXT, "\n", 1]]
     end
 
+    it 'lexes a Windows newline' do
+      lex("\r\n").should == [[:T_TEXT, "\r\n", 1]]
+    end
+
+    it 'lexes a carriage return' do
+      lex("\r").should == [[:T_TEXT, "\r", 1]]
+    end
+
     it 'lexes text followed by a newline' do
       lex("foo\n").should == [[:T_TEXT, "foo\n", 1]]
     end