Add support for EBNF

Extended Backus–Naur form ([EBNF][]) is a metalanguage used to specify
language grammars.

[EBNF]: https://en.wikipedia.org/wiki/Extended_Backus–Naur_form

lib/linguist/languages.yml

@@ -1029,6 +1029,15 @@ E:
   tm_scope: none
   ace_mode: text
   language_id: 92
+EBNF:
+  type: data
+  extensions:
+  - ".ebnf"
+  tm_scope: source.ebnf
+  ace_mode: text
+  codemirror_mode: ebnf
+  codemirror_mime_type: text/x-ebnf
+  language_id: 430
 ECL:
   type: programming
   color: "#8a1267"