Add EEx (Embedded Elixir)

EEx is embedded Elixir: http://elixir-lang.org/docs/v1.0/eex/. Here's
some in-the-wild usage on Github: https://github.com/search?p=100&q=extension%3Aeex+NOT+nothack&ref=searchresults&type=Code&utf8=✓

This uses the "html_elixir" Ace mode, which was added in this pull
request on the Ace project: ajaxorg/ace#2696

grammars.yml

@@ -248,6 +248,7 @@ vendor/grammars/elixir-tmbundle:
 - source.elixir
 - text.elixir
 - text.html.elixir
+- text.html.eex
 vendor/grammars/erlang.tmbundle:
 - source.erlang
 - text.html.erlang.yaws

lib/linguist/languages.yml

@@ -1323,6 +1323,16 @@ HTML+Django:
   - htmldjango
   ace_mode: django
 
+HTML+EEX:
+  type: markup
+  tm_scope: text.html.eex
+  group: HTML
+  aliases:
+  - eex
+  extensions:
+  - .eex
+  ace_mode: html_eex
+
 HTML+ERB:
   type: markup
   tm_scope: text.html.erb

samples/HTML+EEX/index.html.erb

@@ -0,0 +1,26 @@
+<h1>Listing Books</h1>
+
+<table>
+  <tr>
+    <th>Title</th>
+    <th>Summary</th>
+    <th></th>
+    <th></th>
+    <th></th>
+  </tr>
+
+<%= for book <- @books do %>
+  <tr>
+    <%# comment %>
+    <td><%= book.title %></td>
+    <td><%= book.content %></td>
+    <td><%= link "Show", to: book_path(@conn, :show, book) %></td>
+    <td><%= link "Edit", to: book_path(@conn, :edit, book) %></td>
+    <td><%= link "Delete", to: book_path(@conn, :delete, book), method: :delete, data: [confirm: "Are you sure?"] %></td>
+  </tr>
+<% end %>
+</table>
+
+<br />
+
+<%= link "New book", to: book_path(@conn, :new) %>