Fix not being able to save with Shader highlighting

The file types were not an array but just a long string.

Fixes #9.

Author: petereichinger

UnityShader.sublime-syntax

@@ -1,7 +1,7 @@
 %YAML 1.2
 ---
 name: Unity Shader
-file_extensions: [shader cginc]
+file_extensions: [shader, cginc]
 scope: source.unity_shader
 first_line_match: (Shader \".*\")
 variables:
@@ -41,6 +41,6 @@ contexts:
         scope: storage.modifier.source.unity_shader
       - match: (?=ENDCG)
         pop: true
-        
+
   cgprogram_main:
     - include: scope:source.c++