Welcome screen, refactor to allow zero documents, and add TS typing to widgets (#702)

* unfinished implementation

* Add frontend for the empty panel screen

* Add an icon for Folder based on NodeFolder

* fixed messages causing peicees of ui not to render on new document

* Standardize nextTick syntax

* WIP generisization of component subscriptions (not compiling yet)

* Fix crash when loading font and there is no active document

* Only advertise tool actions with a document

* Fix failure to create new document

* Initalise the properties panel

* Fix highlight tab, canvas jump, warns and layer tree

* Fix tests

* Possibly fix some things?

* Move WorkingColors layout definition to backend

* Standardize action macro formatting

* Provide typing for widgets in TS/Vue and associated cleanup

* Fix viewport positioning initialization

* Fix menu bar init at startup not document creation

* Fix no viewport bounds bug

* Change !=0 to >0

* Simplify the init system

Closes #656

Co-authored-by: Keavon Chambers <keavon@keavon.com>
Co-authored-by: 0hypercube <0hypercube@gmail.com>

editor/src/dialog/dialogs/export_dialog.rs

@@ -33,6 +33,7 @@ impl PropertyHolder for Export {
 			WidgetHolder::new(Widget::TextInput(TextInput {
 				value: self.file_name.clone(),
 				on_update: WidgetCallback::new(|text_input: &TextInput| ExportDialogUpdate::FileName(text_input.value.clone()).into()),
+				..Default::default()
 			})),
 		];
 
@@ -123,7 +124,7 @@ impl PropertyHolder for Export {
 				emphasized: true,
 				on_update: WidgetCallback::new(|_| {
 					DialogMessage::CloseDialogAndThen {
-						followup: Box::new(ExportDialogUpdate::Submit.into()),
+						followups: vec![ExportDialogUpdate::Submit.into()],
 					}
 					.into()
 				}),