Change responses to use classes instead of interfaces (#394)

* ability to mark an open document as unsaved

* unsaved detection now being triggered based on layer tree height

* Changed responses to use classes instead of interfaces

* - rust implementation of unsaved markers
- upgraded eslint

* updated eslint in package.json

* - Renamed GetOpenDocumentsList -> UpdateOpenDocumentsList
- is not -> was not

* changed hash to current identifier to better reflect its meaning

* resolve some merge conflicts

* removed console.log statement leftover from debuging

* - changed Response to jsMessage
- split files
- Array<> -> []

* -remove path from UpdateLayer

* - remove unused if statements

* - comment for reflect-metadata
- registerJsMessageHandler -> subscribeJsMessage
- readonly message properties
- fixed binding filename and comment
- toRgb -> toRgba

* - newOpacity -> transformer
- added comments

* MessageMaker -> messageMaker

frontend/src/main.ts

@@ -1,5 +1,8 @@
+// Allows for runtime reflection of types in javascript.
+// It is needed for class-transformer to work and is imported as a side effect.
+// The library replaces the Reflect Api on the window to support more features.
+import "reflect-metadata";
 import { createApp } from "vue";
-
 import { fullscreenModeChanged } from "@/utilities/fullscreen";
 import { onKeyUp, onKeyDown, onMouseMove, onMouseDown, onMouseUp, onMouseScroll, onWindowResize, onBeforeUnload } from "@/utilities/input";
 import "@/utilities/errors";