Merged PR 162: Implement symbols and other stuff (see desc)

Implement symbols
- Add, Remove, Select Container
- Form
- Link with container
- Symbol behavior application to container (move to x with xpositionreference)

Important changes
- Remove SelectedContainer from HistoryState, meaning that it will be slower for each load but will be faster for each operations* (SetHistory, SelectContainer, DeleteContainer, SymbolOperations)
- ElementsSidebar now opens with isSidebarOpen meaning that both sidebar will open on toggle
- Moved camelize, transformX, restoreX to different modules (stringtools.ts, svg.ts)

src/Interfaces/IImage.ts

@@ -1,7 +1,20 @@
-/** Model of an image with multiple source */
+/**
+ * Model of an image with multiple source
+ * It must at least have one source.
+ *
+ * If Url/Base64Image and Svg are set,
+ * Url/Base64Image will be shown in the menu while SVG will be drawn
+ */
 export interface IImage {
+  /** Name of the image */
   Name: string
-  Url: string
-  Base64Image: string
-  Svg: string
+
+  /** (optional) Url of the image */
+  Url?: string
+
+  /** (optional) base64 data of the image */
+  Base64Image?: string
+
+  /** (optional) SVG string */
+  Svg?: string
 }