'text' should be the default lexer

lib/linguist/pathname.rb

@@ -28,7 +28,7 @@ module Linguist
       if language
         language.lexer
       else
-        'plain'
+        'text'
       end
     end
 

test/test_pathname.rb

@@ -48,7 +48,7 @@ class TestPathname < Test::Unit::TestCase
     assert_equal 'bash',   Pathname.new("file.ebuild").lexer
     assert_equal 'python', Pathname.new("itty.py").lexer
     assert_equal 'scheme', Pathname.new("itty.nu").lexer
-    assert_equal 'plain',  Pathname.new("defun.kt").lexer
+    assert_equal 'text',   Pathname.new("defun.kt").lexer
   end
 
   def test_lexer_name