Support rotating editor layer

- As in the annotation layer, use percent instead of pixels as unit;
- handle the rotation of the editor layer in allowing editing when rotation
  angle is not zero;
- the different editors are rotated counterclockwise in order to be usable
  when the main page is itself rotated;
- add support for saving/printing rotated editors.

web/annotation_editor_layer_builder.js

@@ -66,8 +66,9 @@ class AnnotationEditorLayerBuilder {
       return;
     }
 
+    const clonedViewport = viewport.clone({ dontFlip: true });
     if (this.div) {
-      this.annotationEditorLayer.update({ viewport: viewport.clone() });
+      this.annotationEditorLayer.update({ viewport: clonedViewport });
       this.show();
       return;
     }
@@ -86,7 +87,7 @@ class AnnotationEditorLayerBuilder {
     });
 
     const parameters = {
-      viewport: viewport.clone(),
+      viewport: clonedViewport,
       div: this.div,
       annotations: null,
       intent,