Break out mod paint into new crate epaint

epaint/src/stroke.rs

@@ -0,0 +1,31 @@
+use super::*;
+
+/// Describes the width and color of a line.
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+#[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
+pub struct Stroke {
+    pub width: f32,
+    pub color: Color32,
+}
+
+impl Stroke {
+    pub fn none() -> Self {
+        Self::new(0.0, Color32::TRANSPARENT)
+    }
+
+    pub fn new(width: impl Into<f32>, color: impl Into<Color32>) -> Self {
+        Self {
+            width: width.into(),
+            color: color.into(),
+        }
+    }
+}
+
+impl<Color> From<(f32, Color)> for Stroke
+where
+    Color: Into<Color32>,
+{
+    fn from((width, color): (f32, Color)) -> Stroke {
+        Stroke::new(width, color)
+    }
+}