Revert "Add #version 120 to make shaders work on Windows"

USL-32

This breaks OpenGL shaders on Windows and Mac.

resources/shaders/transparent_object.shader

@@ -1,6 +1,5 @@
 [shaders]
 vertex =
-    #version 120
     uniform highp mat4 u_modelMatrix;
     uniform highp mat4 u_viewProjectionMatrix;
     uniform highp mat4 u_normalMatrix;
@@ -22,7 +21,6 @@ vertex =
     }
 
 fragment =
-    #version 120
     uniform mediump vec4 u_ambientColor;
     uniform mediump vec4 u_diffuseColor;
     uniform highp vec3 u_lightPosition;