Move to use an array for selected elements.  Still only single-select mode.
Move to use an array for selected elements.  Still only single-select mode.

trentmillar/ddp-level-editor,ryanramage/svg-editor,trentmillar/ddp-level-editor,ryanramage/svg-editor,trentmillar/ddp-level-editor,ryanramage/svg-editor