Add path closing and segment extension to the Pen tool (#753)

* Close paths with pen tool

* Issue Z command always at end of path

* Small code review style changes

* Extending paths

* Fix mirror on extend path

* Code review tweaks

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

graphene/src/operation.rs

@@ -172,6 +172,10 @@ pub enum Operation {
 		layer_path: Vec<LayerId>,
 		manipulator_group: ManipulatorGroup,
 	},
+	PushFrontManipulatorGroup {
+		layer_path: Vec<LayerId>,
+		manipulator_group: ManipulatorGroup,
+	},
 	RemoveManipulatorGroup {
 		layer_path: Vec<LayerId>,
 		id: u64,
@@ -226,6 +230,12 @@ pub enum Operation {
 		path: Vec<LayerId>,
 		stroke: Stroke,
 	},
+	SetManipulatorHandleMirroring {
+		layer_path: Vec<LayerId>,
+		id: u64,
+		mirror_distance: bool,
+		mirror_angle: bool,
+	},
 	SetSelectedHandleMirroring {
 		layer_path: Vec<LayerId>,
 		toggle_distance: bool,