Add .editorconfig as an INI file

See http://editorconfig.org

lib/linguist/languages.yml

@@ -585,6 +585,8 @@ INI:
   - .prefs
   - .properties
   primary_extension: .ini
+  filenames:
+  - .editorconfig
 
 IRC log:
   lexer: IRC logs

samples/INI/filenames/.editorconfig

@@ -0,0 +1,10 @@
+; editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true