Improve the look of thin lines, making them look weaker (#2437)

* Revert "fix all clippy lints and remove them from allow list in cranky (#2419)"

This reverts commit 930ef2db38.

* Explain the cranky lints better

* Add Color32::gamma_multiply

* Remove unused pub use

* Remove non-existing crate category

* Improve color test with more lines

* Improve the look of thin lines, making them look weaker

Before they looked were too strong for the thickness.

* Use asserts for shader compilations

* Update changelogs

crates/egui_demo_app/src/apps/custom3d_glow.rs

@@ -148,9 +148,10 @@ impl RotatingTriangle {
                     gl.compile_shader(shader);
                     assert!(
                         gl.get_shader_compile_status(shader),
-                        "Failed to compile custom_3d_glow: {}",
+                        "Failed to compile custom_3d_glow {shader_type}: {}",
                         gl.get_shader_info_log(shader)
                     );
+
                     gl.attach_shader(program, shader);
                     shader
                 })