Can set stroke and fill on text and shapes (#551)

* Can set stroke and fill on text and shapes

* resend layout on failed update

* text input properly resets on bad input

* support modifying gradients

* can modify gradients in the properties panel

* updated labels

* remove heap allocation in favor of RC

* removed redundent line

* oops

graphene/src/layers/style/mod.rs

@@ -133,7 +133,7 @@ impl Fill {
 }
 
 #[repr(C)]
-#[derive(Debug, Clone, Copy, PartialEq, Default, Serialize, Deserialize)]
+#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
 pub struct Stroke {
 	color: Color,
 	width: f32,
@@ -157,6 +157,16 @@ impl Stroke {
 	}
 }
 
+// Having an alpha of 1 to start with leads to a better experience with the properties panel
+impl Default for Stroke {
+	fn default() -> Self {
+		Self {
+			width: 0.,
+			color: Color::from_rgba8(0, 0, 0, 255),
+		}
+	}
+}
+
 #[repr(C)]
 #[derive(Debug, Clone, PartialEq, Default, Serialize, Deserialize)]
 pub struct PathStyle {