Gradient Tool (#546)

* Refactor to support fill enum & svg defs

* Init tool

* Fix advertise

* Gradient tool click and drag

* Overlays

* Drag overlays

* Cleanup

* Fix transform on elongated shapes

* Snap rotate

* Snapping

* Add hints

* Rename to solid

* Code review changes

Co-authored-by: Keavon Chambers <keavon@keavon.com>

graphene/src/operation.rs

@@ -1,5 +1,4 @@
 use crate::boolean_ops::BooleanOperation as BooleanOperationType;
-use crate::color::Color;
 use crate::layers::blend_mode::BlendMode;
 use crate::layers::layer_info::Layer;
 use crate::layers::style;
@@ -179,7 +178,7 @@ pub enum Operation {
 	},
 	SetLayerFill {
 		path: Vec<LayerId>,
-		color: Color,
+		fill: style::Fill,
 	},
 }