Add detection for opa (http://www.opalang.org/).

lib/linguist/languages.yml

@@ -342,7 +342,7 @@ Fancy:
 
 Fantom:
   type: programming
-  lexer: Java 
+  lexer: Java
   extensions:
   - .fan
 
@@ -691,6 +691,11 @@ Objective-J:
   - .j
   - .sj
 
+Opa:
+  type: programming
+  extensions:
+  - .opa
+
 OpenCL:
   type: programming
   group: C

test/fixtures/hello_syntax1.opa

@@ -0,0 +1,5 @@
+server = Server.one_page_bundle("Hello World",
+       [],
+       [],
+       _ -> <h1>Hello, world</h1>)
+

test/fixtures/hello_syntax2.opa

@@ -0,0 +1,7 @@
+Server.start(
+   Server.http,
+   {
+     page: function() { <h1>Hello, world</h1> },
+     title: "Hello, world"
+   }
+)