Tech ENABLE_GL_CORE_PROFILE - Use OpenGL core profile context - 1st installment

Fixed conflicts during rebase with master

src/slic3r/GUI/Gizmos/GLGizmoRotate.cpp

@@ -175,7 +175,9 @@ void GLGizmoRotate::on_render()
     transform_to_local(selection);
 #endif // ENABLE_GL_SHADERS_ATTRIBUTES
 
+#if !ENABLE_GL_CORE_PROFILE
     glsafe(::glLineWidth((m_hover_id != -1) ? 2.0f : 1.5f));
+#endif // !ENABLE_GL_CORE_PROFILE
 #if ENABLE_LEGACY_OPENGL_REMOVAL
     GLShaderProgram* shader = wxGetApp().get_shader("flat");
     if (shader != nullptr) {