Fix a crash on exit caused by shader deletion.

src/lol/gpu/shader.h

@@ -314,7 +314,7 @@ private:
 class ShaderData;
 
 //Shader ----------------------------------------------------------------------
-class Shader : public Entity
+class Shader
 {
 public:
     static std::shared_ptr<Shader> Create(std::string const &name, std::string const &code);

src/mesh/mesh.cpp

@@ -61,13 +61,10 @@ SubMesh::SubMesh(std::shared_ptr<Shader> shader, std::shared_ptr<VertexDeclarati
     m_shader(shader),
     m_vdecl(vdecl)
 {
-    Ticker::Ref(m_shader.get());
 }
 
 SubMesh::~SubMesh()
 {
-    Ticker::Unref(m_shader.get());
-    // TODO: cleanup
 }
 
 void SubMesh::SetMeshPrimitive(MeshPrimitive mesh_primitive)
@@ -77,9 +74,7 @@ void SubMesh::SetMeshPrimitive(MeshPrimitive mesh_primitive)
 
 void SubMesh::SetShader(std::shared_ptr<Shader> shader)
 {
-    Ticker::Unref(m_shader.get());
     m_shader = shader;
-    Ticker::Ref(m_shader.get());
 }
 
 std::shared_ptr<Shader> SubMesh::GetShader()