Move layer selection logic from vue to editor (#410)

* Add vue selectLayer(layer, ctrl, shift)

* Individual selection working, range fill next

* Frontend package-lock.json seems apparently needs to be pushed. Weird.

* Selection working with ctrl, shift from editor. Still some bugs to sqaush with folder nesting.

* WIP resolving nesting folders issues

* Changed comparison approach, handling corner cases now

* Fully working selection.

* Reverted changes to package-lock.json

* Removed unused code

* Resolved ctrl click not behaving similar to windows

* Slight comment clarification

* Double checked a windows behavior and corrected. Changed last_selected name.

* Simplified if statement slightly.

* Made the naming clearer regarding UUIDs versus indices

* Clarified comments further

* Minor comment fixup

* Implemented suggestions, clarified comments

* Resolved todo regarding clearing selection when ctrl not pressed

* Ensure we only push responses when needed

Co-authored-by: Keavon Chambers <keavon@keavon.com>
Reviewed by: @TrueDoctor <3

graphene/src/layers/folder.rs

@@ -41,6 +41,7 @@ impl Folder {
 	/// When a insertion id is provided, try to insert the layer with the given id.
 	/// If that id is already used, return None.
 	/// When no insertion id is provided, search for the next free id and insert it with that.
+	/// Negative values for insert_index represent distance from the end
 	pub fn add_layer(&mut self, layer: Layer, id: Option<LayerId>, insert_index: isize) -> Option<LayerId> {
 		let mut insert_index = insert_index as i128;
 		if insert_index < 0 {
@@ -54,13 +55,16 @@ impl Folder {
 			if self.layer_ids.contains(&self.next_assignment_id) {
 				return None;
 			}
+
 			let id = self.next_assignment_id;
 			self.layers.insert(insert_index as usize, layer);
 			self.layer_ids.insert(insert_index as usize, id);
+
 			// Linear probing for collision avoidance
 			while self.layer_ids.contains(&self.next_assignment_id) {
 				self.next_assignment_id += 1;
 			}
+
 			Some(id)
 		} else {
 			None