Ability to save drawings

- Added `toolbox` to the common methods.
- `toolbox.save_drawings_under` can save drawings under a specific `topbar` widget. eg `chart.toolbox.save_drawings_under(chart.topbar[’symbol’]`)
- `toolbox.load_drawings` will load and display drawings stored under the tag/string given.
- `toolbox.export_drawings` will export all currently saved drawings to the given file path.
- `toolbox.import_drawings` will import the drawings stored at the given file path.

Fixes/Enhancements:
- `update` methods are no longer case sensitive.
- HorizontalLines no longer throw cyclic structure errors in the web console.
- `API` methods can now be normal methods or coroutines.

lightweight_charts/js/callback.js

@@ -42,7 +42,7 @@ function makeSearchBox(chart) {
             yPrice = param.point.y;
         }
     });
-    let selectedChart = true
+    let selectedChart = false
     chart.wrapper.addEventListener('mouseover', (event) => {
         selectedChart = true
     })
@@ -50,6 +50,7 @@ function makeSearchBox(chart) {
         selectedChart = false
     })
     chart.commandFunctions.push((event) => {
+        if (!selectedChart) return
         if (searchWindow.style.display === 'none') {
             if (/^[a-zA-Z0-9]$/.test(event.key)) {
                 searchWindow.style.display = 'flex';