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)

test-server/http.js

@@ -112,7 +112,8 @@ const GetSVGLayoutConfiguration = () => {
     ],
     AvailableSymbols: [
       {
-        Height: 0,
+        Width: 32,
+        Height: 32,
         Image: {
           Base64Image: null,
           Name: null,
@@ -120,11 +121,11 @@ const GetSVGLayoutConfiguration = () => {
           Url: 'https://www.manutan.fr/img/S/GRP/ST/AIG3930272.jpg'
         },
         Name: 'Poteau structure',
-        Width: 0,
         XPositionReference: 1
       },
       {
-        Height: 0,
+        Width: 32,
+        Height: 32,
         Image: {
           Base64Image: null,
           Name: null,
@@ -132,7 +133,6 @@ const GetSVGLayoutConfiguration = () => {
           Url: 'https://e7.pngegg.com/pngimages/647/127/png-clipart-svg-working-group-information-world-wide-web-internet-structure.png'
         },
         Name: 'Joint de structure',
-        Width: 0,
         XPositionReference: 0
       }
     ],