Add file?, text? and image? helpers

lib/linguist/pathname.rb

@@ -33,6 +33,23 @@ module Linguist
       @mime_type ||= Mime.lookup(extname)
     end
 
+    def media_type
+      mime_type.split('/').first
+    end
+
+    def file?
+      image? || !text? || mime_type == 'octet-stream'
+    end
+
+    def text?
+      media_type == 'text' ||
+        mime_type == 'application/json'
+    end
+
+    def image?
+      ['.png', '.jpg', '.jpeg', '.gif'].include?(extname)
+    end
+
     def to_s
       @path.dup
     end